AP Chemistry Flashcards: Complete 9-Unit Course Review
Review all nine AP Chemistry units with 450 cards covering concepts, models, equations, calculation setup, and laboratory reasoning.
Tentang dek ini
Review AP® Chemistry through 450 independently written English flashcards arranged in the course's nine-unit sequence. The deck moves from atomic structure and compound structure through properties of substances and mixtures, reactions, kinetics, thermochemistry, equilibrium, acids and bases, and thermodynamics and electrochemistry. Prerequisites come before dependent models and calculations.
What the cards practice
The cards use five recall paths: concept to explanation; model or representation to interpretation; equation to meaning and use; short setup to a result with units and reasoning; and laboratory observation to a chemical conclusion. They cover definitions, relationships, conditions, contrasts, particle and energy models, focused calculation steps, measurements, errors, and visible changes.
Selected reverse and contrast prompts appear only when the reverse direction has one clear standalone target. The deck excludes mechanical permutations, graph-dependent prompts that require a missing figure, copied test formats, long multipart derivations, and visual recall tied to third-party figures. The review scheduler handles long-term spacing after installation.
See the official AP Chemistry course page for College Board's current course requirements.
The Common knowledge · CC0 1.0 label applies only to the independently written prompts, answers, examples, organization, metadata, and inherited original cover, to the extent applicable rights exist. It does not claim ownership of scientific facts or equations.
This is an independent, unofficial study aid. It is not affiliated with, endorsed by, sponsored by, or official material from College Board or the AP Program. AP® is a trademark registered by the College Board, which is not affiliated with, and does not endorse, this product. No College Board examination questions, answer choices, scoring materials, curriculum text, logos, or trade dress were copied.
Kartu dalam dek ini
Kartu 1
Pertanyaan
What does one mole count?
Jawaban
Exactly 6.02214076 × 10^23 representative particles.
Kartu 2
Pertanyaan
What does a peak in an element's mass spectrum represent?
Jawaban
An isotope with a particular mass-to-charge ratio; for singly charged monatomic ions, the position tracks isotopic mass.
Kartu 3
Pertanyaan
What does an empirical formula show?
Jawaban
The lowest whole-number ratio of the elements' atoms in a compound.
Kartu 4
Pertanyaan
How does a mixture differ from a pure substance at the particle level?
Jawaban
A mixture contains chemically distinct representative units in variable proportions; a pure substance contains one element or compound with fixed composition. Different isotopes do not make an elemental sample a mixture.
Kartu 5
Pertanyaan
Which particles make up an atom's nucleus?
Jawaban
Protons and neutrons. Electrons occupy the space outside the nucleus.
Kartu 6
Pertanyaan
What does a larger binding energy on a PES spectrum mean?
Jawaban
More energy is required to remove that electron, so it is held more strongly by the nucleus.
Kartu 7
Pertanyaan
How does atomic radius generally change across a period and down a group?
Jawaban
It decreases from left to right as effective nuclear charge rises, and it increases down a group as additional electron shells increase distance and shielding.
Kartu 8
Pertanyaan
What typical ion charge do Group 1 metals form?
Jawaban
+1, by losing their one valence electron.
Kartu 9
Pertanyaan
How do you convert moles to particles?
Jawaban
Multiply by Avogadro's number: particles = moles × 6.022 × 10^23 mol^-1.
Kartu 10
Pertanyaan
How is average atomic mass estimated from isotope data?
Jawaban
Add each isotopic mass multiplied by its fractional abundance.
Kartu 11
Pertanyaan
How is an element's mass percent in a compound calculated?
Jawaban
Divide the mass contributed by that element by the compound's molar mass, then multiply by 100%.
Kartu 12
Pertanyaan
How can measured elemental composition reveal a sample's purity?
Jawaban
Compare the measured mass fraction with the fraction expected for the pure compound; a mismatch indicates another component.
Kartu 13
Pertanyaan
How do you build a ground-state electron configuration with the Aufbau principle?
Jawaban
For ordinary ground states, move through the periodic table in atomic-number order, filling each s, p, d, or f block as it appears. The subshell capacities are s², p⁶, d¹⁰, and f¹⁴. For example, Br is [Ar] 4s² 3d¹⁰ 4p⁵.
Kartu 14
Pertanyaan
What does the relative area or height of an ideal PES peak indicate?
Jawaban
The relative number of electrons in the corresponding subshell.
Kartu 15
Pertanyaan
How does first ionization energy generally change across a period and down a group?
Jawaban
It increases from left to right as effective nuclear charge rises, and it decreases down a group as distance and shielding make a valence electron easier to remove.
Kartu 16
Pertanyaan
Why do elements in the same group form similar compounds?
Jawaban
Their ground-state valence patterns repeat, including which outer subshells are full or partly full. That leads to similar bonding and typical ion charges.
Kartu 17
Pertanyaan
How do you convert a sample's mass to moles?
Jawaban
Divide its mass by its molar mass: n = m/M.
Kartu 18
Pertanyaan
Which mass-spectrum interpretation lies outside the usual single-element model used in this deck?
Jawaban
Assigning peaks in mixtures or peaks from multiply charged or polyatomic species; the standard model uses singly charged monatomic ions of one element.
Kartu 19
Pertanyaan
What does the law of definite proportions state?
Jawaban
Every pure sample of a given compound has the same element mass ratios.
Kartu 20
Pertanyaan
Why can two samples of the same mixture have different compositions?
Jawaban
Mixture components are physically combined, so their relative amounts are not fixed by a chemical formula.
Kartu 21
Pertanyaan
How does Coulomb's law connect charge and separation to attraction?
Jawaban
Attraction grows with the magnitude of the charge product and decreases with the square of the separation distance.
Kartu 22
Pertanyaan
Which PES electrons usually appear at the highest binding energy?
Jawaban
Core electrons closest to the nucleus, because they feel the strongest nuclear attraction.
Kartu 23
Pertanyaan
How does electron affinity generally change across a period and down a group?
Jawaban
Electron gain generally becomes more favorable from left to right across a period and less favorable down a group as distance and shielding increase. Stable subshell patterns create substantial exceptions.
Kartu 24
Pertanyaan
Why are alkali metals generally more reactive down the group?
Jawaban
Their valence electron is farther from the nucleus and easier to remove.
Kartu 25
Pertanyaan
How many moles are in 18.0 g of H₂O?
Jawaban
About 0.999 mol. Use 18.0 g ÷ 18.02 g mol^-1.
Kartu 26
Pertanyaan
An element is 75% isotope 10 and 25% isotope 11; what is its average atomic mass?
Jawaban
10.25 u. Calculate (0.75 × 10) + (0.25 × 11).
Kartu 27
Pertanyaan
A compound is 40.0% C, 6.7% H, and 53.3% O by mass; what is its empirical formula?
Jawaban
CH₂O. For a 100 g sample, convert each mass to moles and divide by the smallest amount.
Kartu 28
Pertanyaan
A 10.0 g impure sample contains 8.5 g of the target compound; what is its mass-percent purity?
Jawaban
85%. Calculate (8.5 g ÷ 10.0 g) × 100%.
Kartu 29
Pertanyaan
Which electrons are removed first when a transition metal forms a cation?
Jawaban
Electrons in the occupied orbital with the highest principal quantum number: 4s before 3d. For example, Fe²⁺ is [Ar] 3d⁶.
Kartu 30
Pertanyaan
A PES spectrum has peaks proportional to 2, 2, and 6 electrons; which configuration fits?
Jawaban
1s² 2s² 2p⁶, the configuration of Ne.
Kartu 31
Pertanyaan
How does electronegativity generally change across a period and down a group?
Jawaban
It increases from left to right across a period and decreases down a group as atomic size and shielding increase.
Kartu 32
Pertanyaan
What empirical formula results from Al³⁺ and O²⁻?
Jawaban
Al₂O₃, because two Al³⁺ ions balance three O²⁻ ions.
Kartu 33
Pertanyaan
How does a particle's mass in atomic mass units relate to its molar mass?
Jawaban
The numerical value is the same: a molecular or formula-unit mass of x u corresponds to a molar mass of x g mol^-1.
Kartu 34
Pertanyaan
What does the tallest isotope peak usually indicate in a simple mass spectrum?
Jawaban
The most abundant isotope, assuming comparable detection response and singly charged ions.
Kartu 35
Pertanyaan
How much oxygen is present in 25.0 g of a compound that is 32.0% oxygen by mass?
Jawaban
8.00 g O. Multiply 25.0 g by 0.320.
Kartu 36
Pertanyaan
What does a particle diagram with two unbonded species in changing ratios represent?
Jawaban
A mixture, because more than one particle type is present and the ratio is not fixed in a formula unit.
Kartu 37
Pertanyaan
What distinguishes valence electrons from core electrons?
Jawaban
Valence electrons are available for bonding or ion formation; main-group valence electrons occupy the outermost shell, while transition metals may also use (n−1)d electrons. Core electrons mainly shield nuclear charge.
Kartu 38
Pertanyaan
Why can PES peak groups reveal an atom's occupied subshells?
Jawaban
Electrons in different subshells require distinct removal energies, producing separate binding-energy groups.
Kartu 39
Pertanyaan
How do ion radii compare with neutral atoms and within an isoelectronic series?
Jawaban
Cations are smaller than their neutral atoms, while anions are larger. Among species with the same electron count, more protons pull the electrons closer and produce the smaller radius.
Kartu 40
Pertanyaan
What formula is expected for a compound between a Group 2 metal M and a Group 17 nonmetal X?
Jawaban
MX₂, because M forms M²⁺ and X forms X⁻.
Kartu 41
Pertanyaan
When is a covalent bond considered nonpolar?
Jawaban
When the bonded atoms have identical or very similar electronegativities, so the shared electron density is distributed approximately evenly.
Kartu 42
Pertanyaan
Why does a bonded pair of atoms have an equilibrium bond length?
Jawaban
At that separation, attractive and repulsive interactions balance at minimum potential energy.
Kartu 43
Pertanyaan
How are particles arranged in an ionic solid?
Jawaban
Cations and anions occupy a repeating three-dimensional lattice held by electrostatic attraction.
Kartu 44
Pertanyaan
What model explains bonding in a metal?
Jawaban
Positive metal cores are held together by attraction to mobile, delocalized valence electrons.
Kartu 45
Pertanyaan
How do you construct a Lewis diagram?
Jawaban
Count total valence electrons, adding electrons for a negative charge and subtracting them for a positive charge. Choose a skeleton, connect atoms with single bonds, complete terminal duets or octets, and place remaining electrons on the central atom. Add multiple bonds if needed, then check the electron total and formal charges.
Kartu 46
Pertanyaan
What does resonance mean in a molecule or ion?
Jawaban
Resonance uses two or more valid Lewis diagrams with the same atom arrangement but different electron placement. The actual electron distribution is a hybrid; equivalent contributors have equal weight.
Kartu 47
Pertanyaan
What determines molecular shape in VSEPR theory?
Jawaban
Electron domains around the central atom arrange to minimize repulsions.
Kartu 48
Pertanyaan
How does an ionic bond differ from a covalent bond?
Jawaban
Ionic bonding is attraction among oppositely charged ions in an extended structure; covalent bonding uses shared electron density between atoms.
Kartu 49
Pertanyaan
What happens to potential energy when bonded atoms are pushed much closer than equilibrium?
Jawaban
Potential energy rises sharply because nucleus–nucleus and electron–electron repulsions dominate.
Kartu 50
Pertanyaan
Why are many ionic solids brittle?
Jawaban
A shifted lattice can align like charges, creating strong repulsion that splits the crystal.
Kartu 51
Pertanyaan
What molecular shapes arise from two electron domains with no lone pairs and from three domains with zero or one lone pair?
Jawaban
Two bonding domains give linear with a 180° angle. Three domains with no lone pairs give trigonal planar with 120° angles; replacing one bond with a lone pair gives bent with an angle slightly below 120°.
Kartu 52
Pertanyaan
Why are metals electrically conductive as solids?
Jawaban
Their delocalized electrons can move through the solid when an electric field is applied.
Kartu 53
Pertanyaan
How is formal charge calculated for an atom in a Lewis diagram?
Jawaban
Formal charge = valence electrons − nonbonding electrons − half the bonding electrons.
Kartu 54
Pertanyaan
Why can't electronegativity difference alone classify a bond as ionic or covalent?
Jawaban
Bonding lies on a continuum. A larger difference means more ionic character, but the element types and especially the compound's properties give the best classification.
Kartu 55
Pertanyaan
Which shapes and bond-angle trends arise as lone pairs replace bonds in four electron domains?
Jawaban
Four bonds give tetrahedral with ideal 109.5° angles. One lone pair gives trigonal pyramidal with smaller angles; two lone pairs give bent with typically smaller angles again because lone pairs repel more strongly than bonding pairs.
Kartu 56
Pertanyaan
What feature of a potential-energy curve represents bond dissociation energy?
Jawaban
The energy difference from the curve's minimum to the separated-atoms limit.
Kartu 57
Pertanyaan
When does an ionic compound conduct electricity?
Jawaban
When molten or dissolved so its ions can move; not as a rigid solid lattice.
Kartu 58
Pertanyaan
What is a substitutional alloy?
Jawaban
An alloy in which atoms of a similar size replace some host-metal atoms in the lattice.
Kartu 59
Pertanyaan
How do two, three, and four electron domains map to hybridization?
Jawaban
Two domains map to sp, three to sp², and four to sp³, with ideal angles of 180°, 120°, and 109.5°. Hybridization involving d orbitals is outside this deck’s scope.
Kartu 60
Pertanyaan
What usually makes one resonance contributor more favorable than another?
Jawaban
Smaller formal-charge magnitudes, appropriate negative charge on more electronegative atoms, and complete valence shells where applicable.
Kartu 61
Pertanyaan
How many sigma and pi bonds are in single, double, and triple bonds?
Jawaban
A single bond has one sigma bond; a double has one sigma and one pi bond; a triple has one sigma and two pi bonds. Head-on sigma overlap is stronger than side-by-side pi overlap.
Kartu 62
Pertanyaan
Why is a polar covalent bond polar?
Jawaban
Unequal electronegativity creates an uneven sharing of electron density and partial charges.
Kartu 63
Pertanyaan
Which molecular shapes arise as lone pairs replace bonds in five electron domains?
Jawaban
Five bonds give trigonal bipyramidal; four bonds and one lone pair give seesaw; three bonds and two lone pairs give T-shaped; two bonds and three lone pairs give linear.
Kartu 64
Pertanyaan
How do ionic charge and ionic radius affect attraction between ions?
Jawaban
Larger charge magnitudes and smaller ionic radii produce stronger attraction because the charge product increases and the ion centers are closer.
Kartu 65
Pertanyaan
Why do ionic solids often have high melting points?
Jawaban
Many strong Coulombic attractions throughout the lattice must be overcome to free the ions.
Kartu 66
Pertanyaan
What is an interstitial alloy?
Jawaban
A smaller atom occupies holes between host-metal atoms, often making lattice layers harder to slide.
Kartu 67
Pertanyaan
What shape has six bonding domains and no lone pairs on the central atom?
Jawaban
Octahedral.
Kartu 68
Pertanyaan
Which elements commonly form incomplete octets in stable Lewis diagrams?
Jawaban
Hydrogen forms a duet, and electron-deficient central atoms such as boron or beryllium can have fewer than eight electrons.
Kartu 69
Pertanyaan
How do bond order and atomic size affect covalent bond length and strength?
Jawaban
Within a comparable bond family, higher bond order gives shorter, stronger bonds. Larger bonded atoms generally give longer bonds, which are often weaker because their orbitals overlap less effectively.
Kartu 70
Pertanyaan
What bonding model best fits a sample that is malleable and conducts as a solid?
Jawaban
Metallic bonding with mobile, delocalized electrons and nondirectional attractions.
Kartu 71
Pertanyaan
What shape has six electron domains, five bonds, and one lone pair?
Jawaban
Square pyramidal.
Kartu 72
Pertanyaan
Which lattice should have stronger attractions: MgO or NaCl, assuming similar separations?
Jawaban
MgO, because the charge product for Mg²⁺ and O²⁻ is larger than for Na⁺ and Cl⁻.
Kartu 73
Pertanyaan
Why are pure metals often malleable?
Jawaban
Metal cores can shift while the mobile electron sea maintains nondirectional attraction instead of exposing fixed like-charge planes.
Kartu 74
Pertanyaan
What is the best Lewis structure for CO₂?
Jawaban
O=C=O, with two lone pairs on each oxygen and no formal charges.
Kartu 75
Pertanyaan
What shape has six electron domains, four bonds, and two opposite lone pairs?
Jawaban
Square planar.
Kartu 76
Pertanyaan
What limitation does an odd total number of valence electrons create for a Lewis diagram?
Jawaban
At least one electron must remain unpaired, so not every atom can have a complete paired-electron octet.
Kartu 77
Pertanyaan
What does a higher bond order do to a bond's potential-energy curve?
Jawaban
It generally places the minimum at a shorter internuclear distance and makes the well deeper, corresponding to a shorter bond and a larger bond-dissociation energy.
Kartu 78
Pertanyaan
When can a carbon–carbon double bond produce geometric isomers?
Jawaban
When each carbon has two different substituents. The pi bond restricts rotation, so distinct spatial arrangements can persist.
Kartu 79
Pertanyaan
When may a third-period central atom exceed an octet in a Lewis diagram?
Jawaban
When the valid electron count and lower formal charges favor an expanded valence shell, as in species such as SF₆.
Kartu 80
Pertanyaan
How do you decide whether a molecule with polar bonds is polar overall?
Jawaban
Add the bond-dipole vectors using the molecular shape; symmetry may cancel them, while an asymmetric arrangement leaves a net dipole.
Kartu 81
Pertanyaan
Which interparticle forces act between all atoms and molecules?
Jawaban
London dispersion forces, caused by temporary and induced dipoles.
Kartu 82
Pertanyaan
What four broad solid types does this deck compare?
Jawaban
Ionic, metallic, molecular, and covalent-network solids.
Kartu 83
Pertanyaan
How do gas particles differ from liquid particles?
Jawaban
Gas particles are much farther apart and move independently; liquid particles stay close but can move past one another.
Kartu 84
Pertanyaan
What relationship connects pressure, volume, amount, and temperature for an ideal gas?
Jawaban
PV = nRT, with absolute temperature in kelvins and units consistent with R.
Kartu 85
Pertanyaan
What does temperature measure in kinetic molecular theory?
Jawaban
The particles' average translational kinetic energy.
Kartu 86
Pertanyaan
What two ideal-gas assumptions fail most clearly for real gases?
Jawaban
Particles have nonzero volume and experience intermolecular attractions.
Kartu 87
Pertanyaan
How is molarity defined?
Jawaban
Moles of solute per liter of solution: M = n/V.
Kartu 88
Pertanyaan
What must a correct particulate diagram of NaCl(aq) show?
Jawaban
Separated Na⁺ and Cl⁻ ions in a 1:1 ratio, each surrounded by oriented water molecules.
Kartu 89
Pertanyaan
Which separation method removes an insoluble solid from a liquid?
Jawaban
Filtration: the solid stays as residue while the liquid passes as filtrate.
Kartu 90
Pertanyaan
What does “like dissolves like” mean at the particle level?
Jawaban
A solute tends to dissolve when new solute–solvent attractions can compete with the attractions disrupted in the pure substances.
Kartu 91
Pertanyaan
What happens when matter absorbs electromagnetic radiation?
Jawaban
Its particles move to an allowed higher-energy state when the photon energy matches the energy gap.
Kartu 92
Pertanyaan
Which equations connect photon energy, frequency, and wavelength?
Jawaban
E = hν and c = λν.
Kartu 93
Pertanyaan
What is the Beer–Lambert law?
Jawaban
A = εbc: absorbance equals molar absorptivity at the chosen wavelength times path length times concentration.
Kartu 94
Pertanyaan
What molecular features generally strengthen London dispersion forces?
Jawaban
More electrons and a more polarizable cloud strengthen temporary dipoles; greater contact area and accessible π-electron density can also strengthen the attraction.
Kartu 95
Pertanyaan
Why do molecular solids usually have low melting points and fail to conduct electricity?
Jawaban
Distinct molecules are held together by relatively weak intermolecular forces, while their valence electrons stay localized in bonds and lone pairs.
Kartu 96
Pertanyaan
How do particles move in a solid?
Jawaban
They vibrate about fixed positions and do not translate past one another.
Kartu 97
Pertanyaan
What graph shapes connect V or P with T(K) or n for an ideal gas?
Jawaban
All four are straight lines through the origin: V versus T(K) at fixed n and P; P versus T(K) at fixed n and V; V versus n at fixed P and T; and P versus n at fixed V and T.
Kartu 98
Pertanyaan
At the same temperature, which gas has the greater average molecular speed: He or Xe?
Jawaban
He. Both have the same average kinetic energy, but KE = ½mv² means the lower-mass particles move faster.
Kartu 99
Pertanyaan
Why do real gases deviate more at high pressure?
Jawaban
Particles are crowded, so their own volume is no longer negligible compared with the container volume.
Kartu 100
Pertanyaan
Which relationship describes dilution when solute amount is conserved?
Jawaban
M₁V₁ = M₂V₂.
Kartu 101
Pertanyaan
Why does an aqueous ionic solution conduct electricity?
Jawaban
Dissolved ions are mobile and carry charge through the solution.
Kartu 102
Pertanyaan
Which property lets simple distillation separate two liquids?
Jawaban
A sufficient difference in volatility or boiling point, so the vapor is enriched in the more volatile component.
Kartu 103
Pertanyaan
Why are many ionic compounds soluble in water but poorly soluble in a nonpolar solvent?
Jawaban
Water can form strong ion–dipole attractions that stabilize separated ions; a nonpolar solvent cannot provide comparable attractions.
Kartu 104
Pertanyaan
Which molecular transition is commonly associated with microwave absorption?
Jawaban
A transition between quantized rotational energy levels.
Kartu 105
Pertanyaan
What frequency corresponds to a 600. nm photon?
Jawaban
5.00 × 10^14 s^-1. Use ν = c/λ with 600. nm = 6.00 × 10^-7 m.
Kartu 106
Pertanyaan
What is the absorbance to two significant figures when ε = 2.0 × 10² L mol^-1 cm^-1, b = 1.00 cm, and c = 0.0020 M?
Jawaban
0.40. Use A = εbc.
Kartu 107
Pertanyaan
What conditions allow hydrogen bonding between two molecules?
Jawaban
One molecule must donate an H covalently bonded to N, O, or F, and the other must provide a lone pair on N, O, or F. A molecule can be a donor, an acceptor, or both.
Kartu 108
Pertanyaan
Why are covalent-network solids often very hard with high melting points?
Jawaban
A continuous network of strong covalent bonds must be disrupted to deform or melt the solid.
Kartu 109
Pertanyaan
Why do a substance's solid and liquid phases usually have similar molar volumes?
Jawaban
Their particles remain in close contact in both phases, even though liquid particles can move past one another.
Kartu 110
Pertanyaan
How is a gas mixture's total pressure related to its component pressures?
Jawaban
Ptotal = ΣPi; each partial pressure is the pressure that component would exert alone in the same volume and temperature.
Kartu 111
Pertanyaan
What microscopic events create gas pressure?
Jawaban
Gas particles collide with container walls and transfer momentum.
Kartu 112
Pertanyaan
Why do intermolecular attractions matter more for gases at low temperature?
Jawaban
Particles move more slowly, so attractions can alter their paths and promote condensation.
Kartu 113
Pertanyaan
What is the final concentration after 50.0 mL of 2.00 M solution is diluted to 200.0 mL?
Jawaban
0.500 M. Use M₂ = M₁V₁/V₂.
Kartu 114
Pertanyaan
What must a particulate representation of a solution communicate?
Jawaban
The relative concentrations of its components and the particle-level interactions among those components.
Kartu 115
Pertanyaan
What causes components to separate in chromatography?
Jawaban
They differ in attraction to the stationary phase and the mobile phase, so they travel at different rates.
Kartu 116
Pertanyaan
Why are many polar molecular solutes soluble in water?
Jawaban
Dipole attractions or hydrogen bonds with water can replace the solute–solute and water–water attractions disrupted during mixing.
Kartu 117
Pertanyaan
Why does an atom produce discrete spectral lines?
Jawaban
Its electrons can occupy only quantized energy levels, so only photons matching allowed energy differences are absorbed or emitted.
Kartu 118
Pertanyaan
How does photon energy change when frequency doubles?
Jawaban
It doubles because E = hν.
Kartu 119
Pertanyaan
Why is a calibration curve useful in spectrophotometry?
Jawaban
It relates measured absorbance to known concentrations, letting an unknown concentration be read by interpolation within the linear range.
Kartu 120
Pertanyaan
How does an ion–dipole attraction form, and how does it compare with dipole–dipole attraction?
Jawaban
An ion attracts the oppositely charged end of a polar molecule. Ion–dipole attractions tend to be stronger than dipole–dipole attractions.
Kartu 121
Pertanyaan
Which solid type is usually both conductive and malleable?
Jawaban
A metallic solid, because its delocalized electrons move and its nondirectional bonding tolerates layer shifts.
Kartu 122
Pertanyaan
How does a crystalline solid differ from an amorphous solid?
Jawaban
A crystalline solid has long-range repeating order; an amorphous solid lacks that long-range periodic arrangement.
Kartu 123
Pertanyaan
How is a gas component's partial pressure found from mole fraction?
Jawaban
Pi = XiPtotal.
Kartu 124
Pertanyaan
How does heating a fixed-volume gas affect its pressure in the ideal model?
Jawaban
Pressure rises because faster particles collide with the walls more forcefully and frequently.
Kartu 125
Pertanyaan
Why can attractions make a real gas's measured pressure lower than the ideal prediction?
Jawaban
Attractions pull approaching particles away from the walls, reducing momentum transfer during wall collisions.
Kartu 126
Pertanyaan
How many moles of ions result from complete dissolution of 0.20 mol CaCl₂?
Jawaban
0.60 mol ions: 0.20 mol Ca²⁺ plus 0.40 mol Cl⁻.
Kartu 127
Pertanyaan
How should water orient around Cl⁻ in a particle model?
Jawaban
Its partially positive hydrogen ends point toward Cl⁻.
Kartu 128
Pertanyaan
Can filtration separate dissolved components of a liquid solution?
Jawaban
No. Dissolved particles pass through the filter with the solvent; filtration only retains an insoluble solid.
Kartu 129
Pertanyaan
Why do nonpolar molecular solutes often dissolve in nonpolar solvents?
Jawaban
Both rely mainly on compatible London dispersion forces, so mixing can replace the attractions disrupted in the separate substances.
Kartu 130
Pertanyaan
What does a shorter absorbed wavelength imply about an energy transition?
Jawaban
A larger energy gap because E = hc/λ.
Kartu 131
Pertanyaan
What is the energy of a photon with frequency 5.0 × 10^14 s^-1?
Jawaban
3.3 × 10^-19 J. Multiply by Planck's constant: E = (6.626 × 10^-34 J·s)(5.0 × 10^14 s^-1).
Kartu 132
Pertanyaan
How does doubling cuvette path length affect absorbance in the linear Beer–Lambert range?
Jawaban
Absorbance doubles if concentration and molar absorptivity stay constant.
Kartu 133
Pertanyaan
How can noncovalent interactions affect a large biomolecule?
Jawaban
Attractions between molecules or between different regions of the same molecule help set its shape, which strongly affects its properties and function.
Kartu 134
Pertanyaan
Why does an ionic solid usually fail to conduct as a solid?
Jawaban
Its ions are fixed in lattice positions. The same substance conducts when molten or dissolved because the ions can then move.
Kartu 135
Pertanyaan
Why does a gas have no definite shape or volume?
Jawaban
Its widely spaced particles move constantly and experience minimal interparticle attraction, so they spread through the available container.
Kartu 136
Pertanyaan
What graph shapes show the inverse pressure–volume relationship for a fixed amount of ideal gas at constant temperature?
Jawaban
A plot of P against V is a decreasing curve, while P against 1/V is a straight line through the origin.
Kartu 137
Pertanyaan
At the same temperature, do different ideal gases have different average kinetic energies?
Jawaban
No. Average translational kinetic energy depends only on absolute temperature.
Kartu 138
Pertanyaan
Under which conditions is ideal-gas behavior most accurate?
Jawaban
Low pressure and high temperature, where particles are far apart and attractions matter least.
Kartu 139
Pertanyaan
What particle-level feature distinguishes a solution from a heterogeneous mixture?
Jawaban
A solution—whether solid, liquid, or gas—is uniform throughout; a heterogeneous mixture has regions or phases with different compositions.
Kartu 140
Pertanyaan
How should water orient around Na⁺ in a particulate model?
Jawaban
Its partially negative oxygen end points toward Na⁺.
Kartu 141
Pertanyaan
In paper chromatography, why does one solute spot travel farther than another?
Jawaban
It interacts more strongly with the mobile phase or more weakly with the stationary phase. With known phase polarities, that travel difference can reveal relative solute polarity.
Kartu 142
Pertanyaan
What energy competition helps explain whether an ionic solid dissolves?
Jawaban
The energy needed to separate lattice ions competes with the energy released when ion–solvent attractions form.
Kartu 143
Pertanyaan
Which molecular motions commonly absorb infrared radiation?
Jawaban
Bond vibrations whose changing dipole can interact with the radiation.
Kartu 144
Pertanyaan
Why must wavelength be converted to meters in c = λν when c is in m s^-1?
Jawaban
Consistent units are required so meters cancel correctly and frequency comes out in s^-1.
Kartu 145
Pertanyaan
How can fingerprints on a cuvette affect a visible-light absorbance reading?
Jawaban
They can absorb or scatter extra light, making measured absorbance too high and the inferred concentration too high.
Kartu 146
Pertanyaan
What causes and controls the strength of dipole–dipole attractions?
Jawaban
Opposite partial charges on neighboring polar molecules attract. Strength increases with larger molecular dipoles and depends on how favorably the dipoles are oriented.
Kartu 147
Pertanyaan
Why is graphite conductive and soft while diamond is insulating and hard?
Jawaban
Graphite has delocalized electrons within its sheets, so it conducts, and its layers can slide, so it is soft. Diamond has a rigid three-dimensional network of localized covalent bonds, making it hard and insulating.
Kartu 148
Pertanyaan
Why are gases much more compressible than liquids?
Jawaban
Gas particles have large empty spaces between them; liquid particles are already close together.
Kartu 149
Pertanyaan
What volume does 0.500 mol CO₂ occupy at 1.00 atm and 300. K if it behaves ideally?
Jawaban
12.3 L. Use V = nRT/P = (0.500 mol)(0.08206 L atm mol^-1 K^-1)(300. K)/(1.00 atm).
Kartu 150
Pertanyaan
Why does a lighter gas effuse faster than a heavier gas at the same temperature?
Jawaban
Its particles have a higher average speed because equal average kinetic energy is shared by less mass.
Kartu 151
Pertanyaan
How does finite particle volume affect a real gas at very high pressure?
Jawaban
The free volume available for particle motion is smaller than the container volume assumed by the ideal model.
Kartu 152
Pertanyaan
How should 250.0 mL of 0.100 M NaCl be prepared from solid NaCl?
Jawaban
Dissolve 0.0250 mol NaCl, or 1.46 g, then dilute to exactly 250.0 mL in a volumetric flask.
Kartu 153
Pertanyaan
What changes in a particle diagram when a solution is diluted without losing solute?
Jawaban
The solute-particle count stays constant while solvent volume and particle spacing increase.
Kartu 154
Pertanyaan
Why is fractional distillation better than simple distillation for liquids with close boiling points?
Jawaban
Repeated vaporization–condensation steps enrich the vapor in the more volatile component more effectively.
Kartu 155
Pertanyaan
Why are oil and water usually immiscible?
Jawaban
Water's strong hydrogen-bond network isn't replaced by equally strong water–oil attractions, so the substances separate into phases.
Kartu 156
Pertanyaan
Which molecular transition is commonly associated with ultraviolet or visible absorption?
Jawaban
A transition between electronic energy levels.
Kartu 157
Pertanyaan
Which photon carries more energy, blue light or red light?
Jawaban
Blue light, because it has shorter wavelength and higher frequency.
Kartu 158
Pertanyaan
Why is absorbance often measured at the wavelength of maximum absorbance in Beer–Lambert analysis?
Jawaban
It gives the largest concentration-sensitive signal, and the flat top near the maximum makes small wavelength-setting errors less influential.
Kartu 159
Pertanyaan
What creates a dipole–induced-dipole attraction, and what controls its strength?
Jawaban
A permanent dipole distorts a nearby nonpolar particle's electron cloud and creates an attractive temporary dipole. A larger permanent dipole and a more polarizable nonpolar partner make the attraction stronger.
Kartu 160
Pertanyaan
How do stronger intermolecular forces affect vapor pressure, boiling point, and melting point?
Jawaban
They lower vapor pressure and raise boiling point. Melting point often rises too, but the trend is less direct because melting rearranges rather than fully separates particles.
Kartu 161
Pertanyaan
How do particles behave in a liquid?
Jawaban
They stay in close contact while moving and colliding continuously. Temperature and interparticle attractions affect their arrangement and motion.
Kartu 162
Pertanyaan
Why must Celsius temperature be converted to kelvins in gas-law calculations?
Jawaban
Gas-law proportionalities require an absolute temperature scale whose zero corresponds to zero extrapolated thermal motion.
Kartu 163
Pertanyaan
How does raising temperature change a Maxwell–Boltzmann speed distribution?
Jawaban
The distribution broadens, its peak lowers and shifts right, and a larger fraction of particles have high speed.
Kartu 164
Pertanyaan
Why does the ideal-gas model treat collisions as elastic?
Jawaban
It assumes total kinetic energy is conserved in particle–particle and particle–wall collisions.
Kartu 165
Pertanyaan
How many moles of solute are in 75.0 mL of a 0.400 M solution?
Jawaban
0.0300 mol. Multiply 0.400 mol L^-1 by 0.0750 L.
Kartu 166
Pertanyaan
For equal solution volumes drawn at the same scale, what shows which solution is more concentrated?
Jawaban
The more concentrated diagram contains more solute particles in that equal volume.
Kartu 167
Pertanyaan
How do differences in intermolecular attractions let distillation separate a liquid solution?
Jawaban
They give the components different vapor pressures, so the vapor is enriched in the more volatile component.
Kartu 168
Pertanyaan
What comparison helps predict whether two liquids will be miscible?
Jawaban
Liquids with similar types and strengths of intermolecular attractions are more likely to mix uniformly.
Kartu 169
Pertanyaan
How can an absorption spectrum help identify a substance?
Jawaban
Its allowed energy gaps produce a characteristic pattern of absorbed wavelengths that can be compared with known spectra.
Kartu 170
Pertanyaan
How does absorbing or emitting a photon change an atom's or molecule's energy?
Jawaban
Absorption raises the species' energy by exactly the photon energy; emission lowers it by the same amount.
Kartu 171
Pertanyaan
What macroscopic evidence can support that a chemical reaction occurred?
Jawaban
Evidence can include gas formation, precipitate formation, a persistent color change, or an energy change, interpreted with particle-level changes.
Kartu 172
Pertanyaan
What does a net ionic equation include?
Jawaban
Only the dissolved or reacting species that undergo chemical change; spectator ions are omitted.
Kartu 173
Pertanyaan
What must a correct particulate reaction diagram conserve?
Jawaban
The number of atoms of every element and the total charge.
Kartu 174
Pertanyaan
What distinguishes a chemical change from a physical change?
Jawaban
A chemical change rearranges bonds into new substances; a physical change alters state or arrangement without changing chemical identity.
Kartu 175
Pertanyaan
What does a balanced equation's coefficient ratio provide?
Jawaban
The mole ratio among reacting and produced species.
Kartu 176
Pertanyaan
What is the equivalence point of a titration?
Jawaban
The point where titrant and analyte have reacted in the stoichiometric ratio given by the balanced equation.
Kartu 177
Pertanyaan
What defines a precipitation reaction?
Jawaban
Aqueous ions combine to form a sparingly soluble solid.
Kartu 178
Pertanyaan
What happens in a Brønsted–Lowry acid–base reaction?
Jawaban
A proton transfers from the acid (donor) to the base (acceptor). In aqueous solution, H₂O can play either role.
Kartu 179
Pertanyaan
What does oxidation mean in a redox reaction?
Jawaban
Loss of electrons and an increase in oxidation number.
Kartu 180
Pertanyaan
What particle-level change confirms that a process is chemical?
Jawaban
Atoms rearrange into new combinations, producing substances with different compositions.
Kartu 181
Pertanyaan
Which ions are spectators when AgNO₃(aq) reacts with NaCl(aq)?
Jawaban
Na⁺ and NO₃⁻. The net ionic reaction is Ag⁺(aq) + Cl⁻(aq) → AgCl(s).
Kartu 182
Pertanyaan
How does a particulate diagram reveal the limiting reactant?
Jawaban
After forming the maximum product allowed by the ratio, none of the limiting reactant remains while excess reactant particles do.
Kartu 183
Pertanyaan
Is melting ice a chemical or physical change?
Jawaban
A physical change. H₂O molecules remain H₂O while their arrangement and motion change.
Kartu 184
Pertanyaan
How is the limiting reactant identified from given amounts?
Jawaban
Convert each reactant to the same product amount using the balanced equation; the smaller product amount identifies the limiting reactant.
Kartu 185
Pertanyaan
How does an endpoint differ from an equivalence point?
Jawaban
The endpoint is an observed signal such as indicator color change; the equivalence point is the exact stoichiometric condition.
Kartu 186
Pertanyaan
How is complete combustion of a hydrocarbon in excess oxygen classified, and what products form?
Jawaban
It is a redox combustion reaction that forms CO₂ and H₂O.
Kartu 187
Pertanyaan
What are the conjugate acid and conjugate base in NH₃ + H₂O ⇌ NH₄⁺ + OH⁻?
Jawaban
NH₄⁺ is the conjugate acid of NH₃, and OH⁻ is the conjugate base of H₂O.
Kartu 188
Pertanyaan
What does reduction mean in a redox reaction?
Jawaban
Gain of electrons and a decrease in oxidation number.
Kartu 189
Pertanyaan
Which common changes are physical rather than chemical?
Jawaban
Phase changes and the formation or separation of mixtures are physical when each substance keeps its composition.
Kartu 190
Pertanyaan
How are strong soluble electrolytes written in a complete ionic equation?
Jawaban
As separated aqueous ions; solids, liquids, gases, and weak electrolytes stay intact.
Kartu 191
Pertanyaan
A diagram starts with six A particles and four B₂ particles for 2A + B₂ → 2AB; what remains after completion?
Jawaban
One B₂ remains. Six A consume three B₂ and form six AB.
Kartu 192
Pertanyaan
Why is dissolving NaCl in water normally classified as a physical change?
Jawaban
Na⁺ and Cl⁻ separate and become hydrated, but retain their chemical identities. Removing the water recovers NaCl; the shift from ion–ion to ion–dipole attractions does not by itself form a new substance.
Kartu 193
Pertanyaan
What mass of AgCl can form from 25.0 mL of 0.200 M AgNO₃ mixed with excess Cl⁻?
Jawaban
0.717 g AgCl. The 1:1 reaction gives 0.00500 mol AgCl; multiply by 143.32 g mol^-1.
Kartu 194
Pertanyaan
What calculation finds unknown analyte moles at equivalence?
Jawaban
Use titrant moles, n = MV, then apply the balanced-reaction mole ratio.
Kartu 195
Pertanyaan
Which feature identifies an acid–base, redox, or precipitation reaction?
Jawaban
Acid–base reactions transfer protons, redox reactions change oxidation numbers through electron transfer, and precipitation reactions form a sparingly soluble solid.
Kartu 196
Pertanyaan
What is the net ionic equation for strong acid–strong base neutralization?
Jawaban
H⁺(aq) + OH⁻(aq) → H₂O(l).
Kartu 197
Pertanyaan
What is the oxidation number of sulfur in SO₄²⁻?
Jawaban
+6. Four oxygens contribute -8 total, so sulfur must be +6 to give -2 overall.
Kartu 198
Pertanyaan
Why can gas bubbles alone be ambiguous evidence of reaction?
Jawaban
Bubbles may also come from boiling or dissolved gas escaping, so the context and particle identities must support a chemical change.
Kartu 199
Pertanyaan
How is melting ice represented as a balanced physical-change equation?
Jawaban
H₂O(s) → H₂O(l). The formula and atom count stay the same because only the physical state changes.
Kartu 200
Pertanyaan
What does a particle diagram show when no reaction occurs after two aqueous ionic solutions mix?
Jawaban
All ions remain separated and solvated, with no new bonded particles, precipitate, or gas.
Kartu 201
Pertanyaan
Why is rusting iron a chemical change?
Jawaban
Iron atoms form new iron-oxide substances through electron transfer and new bonding.
Kartu 202
Pertanyaan
For 2H₂O₂(aq) → 2H₂O(l) + O₂(g), what volume of O₂ forms from 0.100 mol H₂O₂ at 298 K and 1.00 atm?
Jawaban
1.22 L O₂. The mole ratio gives 0.0500 mol O₂, then V = nRT/P.
Kartu 203
Pertanyaan
A 25.0 mL monoprotic acid sample requires 20.0 mL of 0.150 M NaOH; what is the acid concentration?
Jawaban
0.120 M. At 1:1 equivalence, moles acid = 0.0200 L × 0.150 M, then divide by 0.0250 L.
Kartu 204
Pertanyaan
Which salts does the minimum solubility rule in this deck treat as soluble?
Jawaban
All salts containing Na⁺, K⁺, NH₄⁺, or NO₃⁻ are treated as soluble in water.
Kartu 205
Pertanyaan
How are the strengths of a conjugate acid and its conjugate base related?
Jawaban
A stronger acid has a weaker conjugate base, and a stronger base has a weaker conjugate acid.
Kartu 206
Pertanyaan
How are oxidation and reduction half-reactions combined into one balanced equation?
Jawaban
Multiply them so electrons lost equal electrons gained, add the half-reactions, then cancel electrons and any identical species on both sides.
Kartu 207
Pertanyaan
How do molecular, complete ionic, and net ionic equations differ?
Jawaban
Molecular equations keep compounds intact, complete ionic equations split strong soluble electrolytes, and net ionic equations remove spectators. All three conserve atoms and charge.
Kartu 208
Pertanyaan
How should coefficients change particle counts in a reaction diagram?
Jawaban
They set whole-particle ratios while preserving each particle's chemical formula.
Kartu 209
Pertanyaan
Is separating a mixture by distillation a chemical or physical change?
Jawaban
A physical change. Components change phase and location but keep their chemical identities.
Kartu 210
Pertanyaan
What equation results from Cu → Cu²⁺ + 2e⁻ and Ag⁺ + e⁻ → Ag?
Jawaban
Cu + 2Ag⁺ → Cu²⁺ + 2Ag. Multiply the silver half-reaction by 2 and cancel 2e⁻; both atom counts and net charge then match.
Kartu 211
Pertanyaan
How is average reaction rate found from a reactant concentration?
Jawaban
Use the negative concentration change divided by elapsed time, adjusted by its stoichiometric coefficient when comparing species rates.
Kartu 212
Pertanyaan
What does a rate law express?
Jawaban
It shows how the measured rate depends on reactant concentrations. In rate = k[A]^m[B]^n, m and n are the orders in A and B, and m + n is the overall order.
Kartu 213
Pertanyaan
A plot of ln[A] versus time is linear; what is the order in A and its integrated rate law?
Jawaban
First order: ln[A]t = ln[A]0 − kt, so the plot's slope is −k.
Kartu 214
Pertanyaan
What is an elementary reaction?
Jawaban
A single step in a mechanism whose rate law follows directly from its reactant molecularity.
Kartu 215
Pertanyaan
What two collision conditions are needed for reaction?
Jawaban
Sufficient collision energy and a productive molecular orientation.
Kartu 216
Pertanyaan
What does activation energy represent on a reaction-energy profile?
Jawaban
The energy difference from the reactants to the transition state. The reaction coordinate tracks the step's structural progress, not elapsed time.
Kartu 217
Pertanyaan
What must the elementary steps of a valid mechanism do when added?
Jawaban
Cancel intermediates and reproduce the overall balanced reaction.
Kartu 218
Pertanyaan
How is a proposed mechanism tested against kinetics?
Jawaban
Its derived rate law must agree with the experimentally measured rate law.
Kartu 219
Pertanyaan
What does a pre-equilibrium approximation assume?
Jawaban
A fast reversible step reaches equilibrium before a later slow step consumes its intermediate.
Kartu 220
Pertanyaan
What does each peak on a multistep energy profile represent?
Jawaban
A transition state for one elementary step.
Kartu 221
Pertanyaan
How does a catalyst increase reaction rate?
Jawaban
It provides an alternate mechanism with a lower activation-energy pathway.
Kartu 222
Pertanyaan
Why does crushing a solid reactant usually increase its reaction rate?
Jawaban
Crushing increases exposed surface area, so more reactant particles can collide with the other reactant each second.
Kartu 223
Pertanyaan
How is reaction order found from initial-rate data?
Jawaban
Compare trials where one reactant concentration changes while the others stay constant, then match the rate factor to the concentration factor.
Kartu 224
Pertanyaan
A plot of [A] versus time is linear; what is the order in A and its integrated rate law?
Jawaban
Zero order: [A]t = [A]0 − kt, so the plot's slope is −k.
Kartu 225
Pertanyaan
What is the rate law for the elementary step 2A + B → products?
Jawaban
rate = k[A]²[B]. This inference is valid because the step is elementary.
450 kartu
AP Chemistry Flashcards: Complete 9-Unit Course Review
Pelajari dek ini gratisNibomo akan terbuka agar Anda bisa mulai belajar.
Kartu 226
Pertanyaan
How does raising temperature change a Maxwell–Boltzmann energy distribution and reaction rate?
Jawaban
The distribution shifts and broadens toward higher energies, so a larger fraction of collisions exceeds the activation-energy threshold and can react.
Kartu 227
Pertanyaan
How is ΔH read from a reaction-energy profile?
Jawaban
ΔH = energy of products − energy of reactants.
Kartu 228
Pertanyaan
What is a reaction intermediate?
Jawaban
A species formed in one mechanism step and consumed in a later step, so it cancels from the overall equation.
Kartu 229
Pertanyaan
Why can't overall reaction coefficients usually supply rate-law exponents?
Jawaban
The overall equation hides the mechanism; exponents come from experiment unless the reaction is a stated elementary step.
Kartu 230
Pertanyaan
How does pre-equilibrium remove an intermediate from a rate law?
Jawaban
Use the fast-step equilibrium relation to express the intermediate concentration in terms of stable reactants.
Kartu 231
Pertanyaan
What does each valley between peaks represent on a multistep profile?
Jawaban
A reaction intermediate.
Kartu 232
Pertanyaan
Does a catalyst change ΔH or the equilibrium constant?
Jawaban
No. It changes the pathway and rates, not reactant/product energies or the equilibrium composition.
Kartu 233
Pertanyaan
For 2A → B, how are disappearance of A and appearance of B related?
Jawaban
Reaction rate = -(1/2)Δ[A]/Δt = Δ[B]/Δt.
Kartu 234
Pertanyaan
How do the units of k depend on a rate law's overall order?
Jawaban
They must make the rate unit M s^-1: zero order uses M s^-1, first order s^-1, and second order M^-1 s^-1.
Kartu 235
Pertanyaan
A plot of 1/[A] versus time is linear; what is the order in A and its integrated rate law?
Jawaban
Second order: 1/[A]t = 1/[A]0 + kt, so the plot's slope is +k.
Kartu 236
Pertanyaan
What is molecularity?
Jawaban
The number of reacting particles in an elementary step, such as unimolecular or bimolecular.
Kartu 237
Pertanyaan
How does raising temperature affect k in the qualitative Arrhenius model?
Jawaban
k increases, often sharply, because a larger fraction of collisions can reach the transition state. Arrhenius-equation calculations are outside this deck’s scope.
Kartu 238
Pertanyaan
A reactant falls from 0.80 M to 0.50 M in 30. s; what is its average disappearance rate to two significant figures?
Jawaban
0.010 M s^-1. Use -(0.50 − 0.80) M ÷ 30. s.
Kartu 239
Pertanyaan
How does a catalyst differ from an intermediate in a mechanism?
Jawaban
A catalyst is consumed early and regenerated later; an intermediate is formed early and consumed later.
Kartu 240
Pertanyaan
For 2NO₂ → NO₃ + NO (slow), followed by NO₃ + CO → NO₂ + CO₂ (fast), what rate law is predicted?
Jawaban
rate = k[NO₂]². The first step is elementary and rate-limiting, so its molecularity sets the observed rate law.
Kartu 241
Pertanyaan
On a multistep reaction-energy profile, which feature often identifies the rate-determining step?
Jawaban
The step with the largest activation barrier measured from its preceding valley to its peak.
Kartu 242
Pertanyaan
If changing [B] leaves rate unchanged, what is the order in B?
Jawaban
Zero order, so [B]^0 = 1 in the measured rate law.
Kartu 243
Pertanyaan
What mechanism changes can binding, acid–base, or surface catalysis introduce?
Jawaban
They can orient reactants, lower activation barriers, or create new bound, protonated, or deprotonated intermediates and elementary steps; the catalyst is regenerated.
Kartu 244
Pertanyaan
What is special about a first-order reaction's half-life?
Jawaban
It is constant and independent of starting concentration: t1/2 = ln 2/k. Radioactive decay is a common first-order example.
Kartu 245
Pertanyaan
Why is a termolecular elementary collision uncommon?
Jawaban
Three particles must collide simultaneously with suitable energy and orientation, which is much less probable than one- or two-particle events.
Kartu 246
Pertanyaan
On a reaction-energy profile, how are reverse activation energy, forward activation energy, and ΔH related?
Jawaban
Ea,reverse = Ea,forward − ΔH. The reverse barrier is measured from products to the same transition state.
Kartu 247
Pertanyaan
Why can correct orientation matter even above the activation energy?
Jawaban
The colliding reactive sites must align so old bonds can break and new bonds can form along the reaction pathway.
Kartu 248
Pertanyaan
How does detecting a proposed reaction intermediate affect a mechanism claim?
Jawaban
It supports a mechanism that contains that intermediate, but it doesn't prove that mechanism is unique.
Kartu 249
Pertanyaan
For 2NO ⇌ N₂O₂ (fast equilibrium), followed by N₂O₂ + O₂ → 2NO₂ (slow), what observed rate law results?
Jawaban
rate = kobs[NO]²[O₂]. Start with rate = k₂[N₂O₂][O₂], use [N₂O₂] = K[NO]² from the fast equilibrium, then substitute.
Kartu 250
Pertanyaan
What does the highest point of a one-step energy profile represent?
Jawaban
The transition state, an unstable arrangement at the top of the activation barrier.
Kartu 251
Pertanyaan
What sign does q have for an endothermic system?
Jawaban
Positive, because the system absorbs heat from the surroundings.
Kartu 252
Pertanyaan
How does an exothermic reaction appear on an enthalpy diagram?
Jawaban
Products lie below reactants, so ΔH is negative.
Kartu 253
Pertanyaan
What condition defines thermal equilibrium?
Jawaban
Objects in contact have the same temperature, so there is no net heat transfer.
Kartu 254
Pertanyaan
What equations relate heat capacity and temperature change to heat transfer?
Jawaban
Use q = mcΔT with specific heat capacity, or q = nCₘΔT with molar heat capacity.
Kartu 255
Pertanyaan
Why is temperature constant during a phase-change plateau?
Jawaban
Added or removed energy changes interparticle potential energy instead of average kinetic energy.
Kartu 256
Pertanyaan
What does ΔHrxn describe?
Jawaban
The heat absorbed or released at constant pressure for the reaction exactly as written under the stated conditions.
Kartu 257
Pertanyaan
How is reaction enthalpy estimated from average bond enthalpies?
Jawaban
ΔHrxn ≈ Σ(bonds broken) − Σ(bonds formed).
Kartu 258
Pertanyaan
What is the standard enthalpy of formation of an element in its standard state?
Jawaban
Zero by definition.
Kartu 259
Pertanyaan
In a Hess’s law calculation, how should a step change when the target needs twice its reverse?
Jawaban
Reverse the equation, double every coefficient, and multiply its ΔH by -2.
Kartu 260
Pertanyaan
How can energy cross a system boundary during a process?
Jawaban
As heat or work. Heat transferred to or work done on the system increases its energy; heat transferred from or work done by the system decreases it.
Kartu 261
Pertanyaan
How does an endothermic reaction appear on an enthalpy diagram?
Jawaban
Products lie above reactants, so ΔH is positive.
Kartu 262
Pertanyaan
How are heat gained by a system and heat lost by its surroundings related in an isolated setup?
Jawaban
qsystem = -qsurroundings.
Kartu 263
Pertanyaan
In coffee-cup calorimetry, how is reaction heat related to solution heat?
Jawaban
qrxn = -qsolution when calorimeter heat is negligible and pressure is constant.
Kartu 264
Pertanyaan
What heat is required to melt n moles at the melting point?
Jawaban
q = nΔHfus.
Kartu 265
Pertanyaan
How does reversing a reaction change ΔH?
Jawaban
It reverses the sign of ΔH.
Kartu 266
Pertanyaan
Why is breaking a bond endothermic?
Jawaban
Energy must be supplied to separate atoms against their bonding attraction.
Kartu 267
Pertanyaan
How is ΔH°rxn calculated from standard enthalpies of formation?
Jawaban
ΣνΔHf°(products) − ΣνΔHf°(reactants).
Kartu 268
Pertanyaan
How does multiplying an equation by 3 affect its ΔH?
Jawaban
Multiply ΔH by 3 because enthalpy change scales with reaction amount.
Kartu 269
Pertanyaan
Why can an exothermic dissolution warm the solution?
Jawaban
The solution warms because forming solute–solvent attractions releases more energy than is absorbed in separating the original particles. The net potential-energy decrease raises particle kinetic energy and temperature.
Kartu 270
Pertanyaan
Does an energy diagram's activation barrier determine ΔH?
Jawaban
No. ΔH depends on reactant and product energy levels, while the barrier controls kinetics.
Kartu 271
Pertanyaan
Why does heat flow from a warmer object to a cooler object?
Jawaban
Energy transfers through collisions until their average kinetic energies, and therefore temperatures, equalize.
Kartu 272
Pertanyaan
How much heat warms 100.0 g of water by 5.0°C?
Jawaban
2.1 kJ. Use q = (100.0 g)(4.184 J g^-1 °C^-1)(5.0°C).
Kartu 273
Pertanyaan
How are the molar enthalpies of a phase change and its reverse related?
Jawaban
They have equal magnitudes and opposite signs, such as ΔHcond = -ΔHvap and ΔHfreeze = -ΔHfus.
Kartu 274
Pertanyaan
How does doubling every coefficient in a thermochemical equation affect ΔH?
Jawaban
It doubles ΔH.
Kartu 275
Pertanyaan
Why is forming a bond exothermic?
Jawaban
Atoms move to a lower-potential-energy bonded arrangement and release energy.
Kartu 276
Pertanyaan
What formation equation defines ΔHf° for CO₂(g)?
Jawaban
C(s, graphite) + O₂(g) → CO₂(g), forming exactly one mole from elements in standard states.
Kartu 277
Pertanyaan
What should happen to intermediate species when equations in a Hess’s law calculation are added?
Jawaban
They cancel, leaving the target overall reaction.
Kartu 278
Pertanyaan
If the surroundings warm during a process, what is the likely sign of qsystem?
Jawaban
Negative; the system likely released heat to the surroundings.
Kartu 279
Pertanyaan
For a profile with reactants at 40 kJ and products at 10 kJ, what is ΔH?
Jawaban
-30 kJ for the reaction as drawn.
Kartu 280
Pertanyaan
Assuming no phase change, what determines the final temperature when two substances exchange heat in an insulated container?
Jawaban
Energy conservation: q_warm + q_cool = 0. Use each substance's mass, heat capacity, and initial temperature to solve for the common final temperature.
Kartu 281
Pertanyaan
How would heat loss to the room affect an exothermic calorimetry result?
Jawaban
The observed temperature rise is too small, so the calculated magnitude of released heat is too low.
Kartu 282
Pertanyaan
What heat expression covers warming a liquid without a phase change?
Jawaban
q = mcΔT, not nΔHphase.
Kartu 283
Pertanyaan
If forming 1 mol of product has ΔH = -50 kJ mol^-1, what is q when 2 mol forms?
Jawaban
-100 kJ. Use q = nΔH = (2 mol)(-50 kJ mol^-1).
Kartu 284
Pertanyaan
Breaking reactant bonds requires 500 kJ, and forming product bonds releases 650 kJ; what is the estimated ΔH?
Jawaban
-150 kJ, from 500 − 650.
Kartu 285
Pertanyaan
For CO(g) + ½O₂(g) → CO₂(g), what is ΔH°rxn if ΔHf°[CO] = -110.5 and ΔHf°[CO₂] = -393.5 kJ mol^-1?
Jawaban
-283.0 kJ. Use -393.5 - [-110.5 + ½(0)], since ΔHf°[O₂(g)] = 0.
Kartu 286
Pertanyaan
In a Hess’s law calculation, two valid steps have ΔH values +25 kJ and -60 kJ; what is the combined ΔH?
Jawaban
-35 kJ, provided the equations add to the target reaction.
Kartu 287
Pertanyaan
Why is “bonds breaking releases energy” incorrect?
Jawaban
Bond breaking absorbs energy; the overall reaction releases energy only when forming new bonds releases more than breaking old bonds requires.
Kartu 288
Pertanyaan
How would melting appear on an energy diagram?
Jawaban
The liquid lies above the solid, so ΔHfus is positive; the diagram represents a physical, endothermic change.
Kartu 289
Pertanyaan
Can two objects at the same temperature exchange energy microscopically?
Jawaban
Yes, but their energy transfers balance, so there is no net heat flow.
Kartu 290
Pertanyaan
Why must the calorimeter's heat capacity be included when it isn't negligible?
Jawaban
The apparatus can absorb or release heat, so include q_cal = C_calΔT in the energy balance: q_process + q_solution + q_cal = 0.
Kartu 291
Pertanyaan
What makes chemical equilibrium dynamic?
Jawaban
Forward and reverse reactions continue at equal rates even though macroscopic concentrations stay constant.
Kartu 292
Pertanyaan
For aA + bB ⇌ cC, what is the concentration-form expression for Q?
Jawaban
Q = [C]^c / ([A]^a[B]^b), using current rather than necessarily equilibrium concentrations.
Kartu 293
Pertanyaan
What does K much greater than 1 indicate?
Jawaban
Products predominate at equilibrium, though K says nothing about reaction speed.
Kartu 294
Pertanyaan
How does reversing a reaction change its equilibrium constant?
Jawaban
K becomes 1/K.
Kartu 295
Pertanyaan
Can a reversible system reach equilibrium when it starts with only products?
Jawaban
Yes, if the reverse reaction is possible. The equilibrium composition depends on temperature, initial amounts, and volume or pressure.
Kartu 296
Pertanyaan
How do Q and K predict reaction direction?
Jawaban
Q < K shifts forward, Q > K shifts reverse, and Q = K means equilibrium.
Kartu 297
Pertanyaan
Which species are omitted from a heterogeneous equilibrium expression?
Jawaban
Pure solids and pure liquids because their activities are effectively constant.
Kartu 298
Pertanyaan
How does increasing a dissolved reactant's concentration or a gaseous reactant's partial pressure affect equilibrium at constant temperature when other Q terms are initially unchanged?
Jawaban
It lowers Q relative to K, so the system shifts toward products until Q = K again. Changing the amount of a pure solid or liquid omitted from Q does not cause this shift while that pure phase remains present.
Kartu 299
Pertanyaan
What does a flat concentration-time graph mean at equilibrium?
Jawaban
Each concentration is constant, not necessarily equal to the others.
Kartu 300
Pertanyaan
For A ⇌ B in one fixed volume, a particulate model shows 16 A and 0 B initially, then 4 A and 12 B at equilibrium. What changed, what predominates, and what is Kc?
Jawaban
The net change was forward: 12 A particles became 12 B particles. B predominates at equilibrium, and Kc = [B]/[A] = 12/4 = 3.0 because both counts come from the same fixed volume.
Kartu 301
Pertanyaan
What can Ksp tell you about a salt's solubility, and when can two Ksp values be compared directly?
Jawaban
Ksp > 1 indicates a soluble salt. For salts with the same dissolution stoichiometry, a larger Ksp generally means greater molar solubility; across different stoichiometries, calculate molar solubility before comparing.
Kartu 302
Pertanyaan
What is the common-ion effect on solubility?
Jawaban
Adding an ion already in the dissolution equilibrium usually decreases the solid's molar solubility.
Kartu 303
Pertanyaan
How does uniform dilution shift an aqueous equilibrium based on the stoichiometric powers in Q?
Jawaban
It shifts toward the side with the larger sum of stoichiometric coefficients for dissolved species included in Q. If the sums are equal, dilution causes no shift by this effect; pure solids and liquids remain omitted.
Kartu 304
Pertanyaan
What happens if a reversible reaction starts with reactants only?
Jawaban
The forward rate is initially largest; products form, the reverse rate grows, and the rates eventually become equal.
Kartu 305
Pertanyaan
What is the purpose of an ICE table?
Jawaban
To organize initial, change, and equilibrium concentrations using reaction stoichiometry.
Kartu 306
Pertanyaan
Can a reaction with a very large K be slow?
Jawaban
Yes. K describes thermodynamic equilibrium position, while rate depends on kinetics and activation energy.
Kartu 307
Pertanyaan
What happens to Q immediately after product concentration increases?
Jawaban
Q increases; if it rises above K, the reaction shifts toward reactants.
Kartu 308
Pertanyaan
How does multiplying every reaction coefficient by 2 affect K?
Jawaban
The new equilibrium constant is K².
Kartu 309
Pertanyaan
For A ⇌ B, Kc = 4.0 and initially [A] = 1.0 M and [B] = 0, what are the equilibrium concentrations?
Jawaban
[A] = 0.20 M and [B] = 0.80 M. Let x form: Kc = x/(1.0 − x) = 4.0, so x = 0.80 M.
Kartu 310
Pertanyaan
What macroscopic properties stay constant at equilibrium?
Jawaban
Properties such as concentration, color, and pressure remain constant when external conditions are fixed.
Kartu 311
Pertanyaan
How does decreasing volume shift a gaseous equilibrium?
Jawaban
Toward the side with fewer moles of gas, if the two sides have different gaseous mole counts.
Kartu 312
Pertanyaan
For N₂ + 3H₂ ⇌ 2NH₃, what is Kc?
Jawaban
Kc = [NH₃]² / ([N₂][H₂]³).
Kartu 313
Pertanyaan
For CaF₂(s) ⇌ Ca²⁺ + 2F⁻, how is Ksp written in terms of molar solubility s in pure water?
Jawaban
Ksp = s(2s)² = 4s³ because [Ca²⁺] = s and [F⁻] = 2s.
Kartu 314
Pertanyaan
What does K much less than 1 indicate?
Jawaban
Reactants predominate at equilibrium.
Kartu 315
Pertanyaan
How does decreasing a dissolved product's concentration or a gaseous product's partial pressure affect equilibrium when other Q terms are initially unchanged?
Jawaban
It lowers Q and drives a net forward reaction until equilibrium returns. Changing the amount of a pure solid or liquid omitted from Q does not cause this shift while that phase remains.
Kartu 316
Pertanyaan
Does equilibrium mean the reaction has stopped?
Jawaban
No. Both directions continue, but equal rates produce no net macroscopic change.
Kartu 317
Pertanyaan
Why does adding NaF reduce CaF₂ solubility?
Jawaban
The added F⁻ raises Qsp, shifting the dissolution equilibrium toward solid CaF₂.
Kartu 318
Pertanyaan
For N₂ + 3H₂ ⇌ 2NH₃, what is Kp when P_N₂ = 0.50 atm, P_H₂ = 1.50 atm, and P_NH₃ = 0.25 atm?
Jawaban
0.037. Use Kp = (P_NH₃)²/[(P_N₂)(P_H₂)³] = (0.25)²/[(0.50)(1.50)³]. Use equilibrium partial pressures directly; Kc↔Kp conversion isn't assessed.
Kartu 319
Pertanyaan
What happens to Q when a gaseous equilibrium mixture is compressed at constant temperature if products have fewer gas moles?
Jawaban
Q falls relative to K, so the reaction shifts toward products.
Kartu 320
Pertanyaan
How do K and Q transform when a reaction is reversed, its coefficients are multiplied, or reactions are added?
Jawaban
They follow the same algebra: reversing takes the reciprocal, multiplying every coefficient by c raises the value to the power c, and adding reactions multiplies their K or Q values.
Kartu 321
Pertanyaan
When is the small-x approximation acceptable?
Jawaban
When x is small relative to the initial concentration and the final result confirms the neglected change is suitably small.
Kartu 322
Pertanyaan
What graph feature shows a disturbance followed by re-equilibration?
Jawaban
A sudden or gradual concentration change followed by new constant plateaus while rates return to equality.
Kartu 323
Pertanyaan
If Q = 0.20 and K = 5.0, which direction is favored next?
Jawaban
Forward, because Q < K.
Kartu 324
Pertanyaan
At equilibrium, are reactant and product concentrations equal?
Jawaban
Not necessarily. They are constant, while forward and reverse rates are equal.
Kartu 325
Pertanyaan
CaF₂ has Ksp = 3.2 × 10^-11 in pure water; what is its molar solubility?
Jawaban
2.0 × 10^-4 M. If the molar solubility is s, then [Ca²⁺] = s, [F⁻] = 2s, and Ksp = 4s³.
Kartu 326
Pertanyaan
For N₂ + 3H₂ ⇌ 2NH₃, how is Qp written?
Jawaban
Qp = (P_NH₃)²/[(P_N₂)(P_H₂)³], using the current partial pressures rather than necessarily equilibrium values.
Kartu 327
Pertanyaan
How does heating shift an endothermic forward reaction?
Jawaban
Toward products, and K increases because temperature changes the equilibrium constant.
Kartu 328
Pertanyaan
Why do both forward and reverse rates change as equilibrium is approached?
Jawaban
As reactant and product concentrations change, the collision frequencies for the two directions change until their rates match.
Kartu 329
Pertanyaan
CaF₂ has Ksp = 3.2 × 10^-11. What is its molar solubility in 0.10 M NaF?
Jawaban
About 3.2 × 10^-9 M. With [F⁻] ≈ 0.10 M, Ksp = [Ca²⁺][F⁻]² gives s = (3.2 × 10^-11)/(0.10)². The common ion lowers solubility but does not change Ksp at constant temperature.
Kartu 330
Pertanyaan
What concentration data must be used to calculate Kc?
Jawaban
Equilibrium concentrations, each raised to its stoichiometric coefficient and excluding pure solids and liquids.
Kartu 331
Pertanyaan
What is a Brønsted–Lowry acid?
Jawaban
A proton donor.
Kartu 332
Pertanyaan
How is pH defined?
Jawaban
pH = -log[H₃O⁺].
Kartu 333
Pertanyaan
What is Ka for HA + H₂O ⇌ H₃O⁺ + A⁻?
Jawaban
Ka = [H₃O⁺][A⁻]/[HA].
Kartu 334
Pertanyaan
How does stabilizing a base affect its basicity and the strength of its conjugate acid?
Jawaban
It makes the base weaker and its conjugate acid stronger. A more stable base is less willing to accept H⁺.
Kartu 335
Pertanyaan
What is a Brønsted–Lowry base?
Jawaban
A proton acceptor.
Kartu 336
Pertanyaan
At 25°C, what are Kw and the relationship between pH and pOH?
Jawaban
Kw = [H₃O⁺][OH⁻] = 1.0 × 10^-14. Taking negative logarithms gives pH + pOH = 14.00.
Kartu 337
Pertanyaan
What is Kb for B + H₂O ⇌ BH⁺ + OH⁻?
Jawaban
Kb = [BH⁺][OH⁻]/[B].
Kartu 338
Pertanyaan
Why can lowering pH increase the solubility of a salt containing a basic anion?
Jawaban
H₃O⁺ consumes the anion, pulling the dissolution equilibrium toward more dissolved ions.
Kartu 339
Pertanyaan
What are conjugate acid–base pairs?
Jawaban
Species that differ by exactly one proton.
Kartu 340
Pertanyaan
What is the pH of 1.0 × 10^-3 M HCl?
Jawaban
3.00, assuming complete dissociation and negligible water contribution.
Kartu 341
Pertanyaan
How are pKa and pKb defined?
Jawaban
pKa = -log Ka, and pKb = -log Kb.
Kartu 342
Pertanyaan
Why does acid strength increase across a row of comparable hydrides?
Jawaban
Increasing electronegativity stabilizes the conjugate base and polarizes the H–A bond.
Kartu 343
Pertanyaan
What is an amphiprotic species?
Jawaban
A species that can donate or accept a proton, such as HCO₃⁻.
Kartu 344
Pertanyaan
What amounts remain after a limited amount of strong base partially neutralizes weak acid HA?
Jawaban
Subtract the reacted moles from HA and form the same number of moles of A⁻. The result gives the remaining HA and formed A⁻ amounts before any equilibrium or buffer-pH calculation.
Kartu 345
Pertanyaan
How are Ka, Kb, pKa, and pKb related for a conjugate pair at 25°C?
Jawaban
KaKb = Kw = 1.0 × 10^-14, and pKa + pKb = pKw = 14.00.
Kartu 346
Pertanyaan
When does pH have little effect on a salt's solubility?
Jawaban
When neither dissolved ion reacts appreciably with H₃O⁺ or OH⁻.
Kartu 347
Pertanyaan
How does H₂O act in HCl + H₂O → H₃O⁺ + Cl⁻ and in NH₃ + H₂O ⇌ NH₄⁺ + OH⁻?
Jawaban
It acts as a base in the first reaction by accepting H⁺, and as an acid in the second by donating H⁺.
Kartu 348
Pertanyaan
After mixing weak base B with strong acid, what controls the final solution in the three stoichiometric regimes?
Jawaban
Excess B leaves a B/BH⁺ buffer; equimolar amounts leave BH⁺, so the solution is acidic; excess strong acid sets the pH from the remaining H₃O⁺.
Kartu 349
Pertanyaan
What two components make a typical weak-acid buffer?
Jawaban
A weak acid and a significant amount of its conjugate base.
Kartu 350
Pertanyaan
What do the successive half-equivalence pH values approximate in a diprotic weak-acid titration?
Jawaban
The first approximates pKa₁ and the second approximates pKa₂ because each conjugate pair has equal concentrations at its half-equivalence point.
Kartu 351
Pertanyaan
Which acid is stronger, one with pKa 2 or pKa 5?
Jawaban
The acid with pKa 2; lower pKa means larger Ka.
Kartu 352
Pertanyaan
What is the Henderson–Hasselbalch equation?
Jawaban
pH = pKa + log([A⁻]/[HA]).
Kartu 353
Pertanyaan
Why are larger binary hydrides down a group often stronger acids?
Jawaban
The H–A bond becomes weaker as the central atom grows, so proton release is easier.
Kartu 354
Pertanyaan
What mainly determines buffer capacity?
Jawaban
The concentrations of both members of the conjugate acid–base pair. Increasing both concentrations at a fixed ratio increases capacity without changing pH; capacity is best balanced for added acid and base when their concentrations are similar.
Kartu 355
Pertanyaan
Why does acid increase CaCO₃ solubility?
Jawaban
H₃O⁺ converts CO₃²⁻ to HCO₃⁻ or carbonic acid species, reducing free carbonate and driving more CaCO₃ to dissolve.
Kartu 356
Pertanyaan
What does pH < pKa imply for a weak-acid pair?
Jawaban
The protonated form HA predominates over A⁻.
Kartu 357
Pertanyaan
What happens when stoichiometrically equal amounts of a monoprotic weak acid and strong base are mixed?
Jawaban
The weak acid is consumed to its conjugate base; at equivalence, the solution isn't a buffer containing both forms.
Kartu 358
Pertanyaan
What is [H₃O⁺] when pH = 4.50?
Jawaban
3.2 × 10^-5 M, from [H₃O⁺] = 10^-pH.
Kartu 359
Pertanyaan
What is the pH of 0.010 M Ba(OH)₂ at 25°C?
Jawaban
About 12.30. Complete dissociation gives [OH⁻] = 0.020 M, so pOH = 1.70. At 25°C, pH + pOH = 14.00, so pH = 12.30.
Kartu 360
Pertanyaan
How does a buffer respond to a small amount of added strong acid?
Jawaban
Its conjugate base consumes H⁺, converting to the weak acid and limiting the pH change.
Kartu 361
Pertanyaan
Why is the equivalence-point solution basic in a monoprotic weak-acid–strong-base titration?
Jawaban
The conjugate base produced at equivalence reacts with water to form OH⁻, so the pH is above neutral—above 7.00 at 25°C.
Kartu 362
Pertanyaan
How is percent ionization calculated for a weak acid or weak base?
Jawaban
For HA, use ([H₃O⁺]equilibrium ÷ [HA]initial) × 100%. For B, use ([BH⁺]equilibrium ÷ [B]initial) × 100%, under the usual monoprotic setup.
Kartu 363
Pertanyaan
When is Henderson–Hasselbalch useful for an initial buffer-pH calculation?
Jawaban
Use it when both members of a conjugate acid–base pair are present in meaningful amounts, including after in-scope stoichiometry creates a buffer. Calculating the pH change after acid or base is added to an existing buffer is outside this deck’s scope.
Kartu 364
Pertanyaan
Why does adding oxygen atoms usually strengthen oxyacids with the same central atom?
Jawaban
Extra oxygens withdraw electron density and delocalize negative charge in the conjugate base.
Kartu 365
Pertanyaan
A prepared buffer is accidentally diluted to twice its intended volume; what happens to its pH and capacity?
Jawaban
Its pH stays nearly the same, and its capacity per liter is halved because both component concentrations halve. The total neutralizing moles in the sample remain unchanged.
Kartu 366
Pertanyaan
How does adding OH⁻ affect Mg(OH)₂ solubility?
Jawaban
It decreases solubility through the common-ion effect, shifting Mg(OH)₂(s) ⇌ Mg²⁺ + 2OH⁻ toward the solid.
Kartu 367
Pertanyaan
A buffer has equal [A⁻] and [HA]; what is its pH?
Jawaban
pH = pKa because log(1) = 0.
Kartu 368
Pertanyaan
How should a weak acid–strong base mixture be solved before equivalence?
Jawaban
First use mole stoichiometry; if both HA and A⁻ remain, use the resulting buffer relation.
Kartu 369
Pertanyaan
Why can pure neutral water have a pH other than 7.00?
Jawaban
Kw changes with temperature. Neutrality means [H₃O⁺] = [OH⁻], while pH = 7.00 only when Kw = 1.0 × 10^-14 at 25°C.
Kartu 370
Pertanyaan
25.0 mL of 0.200 M HCl is diluted to 100.0 mL; what is the pH?
Jawaban
1.301. Dilution gives [H₃O⁺] = (0.200 M)(25.0 mL)/(100.0 mL) = 0.0500 M, so pH = -log(0.0500).
Kartu 371
Pertanyaan
How does a buffer respond to a small amount of added strong base?
Jawaban
The weak acid consumes OH⁻, forming conjugate base and water.
Kartu 372
Pertanyaan
How do you find the final pH after mixing a strong acid and strong base at 25°C?
Jawaban
Use H₃O⁺ + OH⁻ → 2H₂O and compare their moles. Divide excess H₃O⁺ or OH⁻ by the total volume, then calculate pH or pOH from that excess concentration. Equal moles give pH 7.00 at 25°C.
Kartu 373
Pertanyaan
What distinguishes acid strength from acid concentration?
Jawaban
Strength is the equilibrium tendency to donate H⁺, reflected by Ka or pKa; concentration is the amount of acid per solution volume.
Kartu 374
Pertanyaan
If [A⁻]/[HA] = 10, how does pH compare with pKa?
Jawaban
pH = pKa + 1 because log 10 = 1.
Kartu 375
Pertanyaan
Which conjugate base is more stable, one with localized or resonance-delocalized charge?
Jawaban
The resonance-delocalized conjugate base, which generally corresponds to the stronger acid.
Kartu 376
Pertanyaan
Which 1.0 L buffer has greater capacity: 1.0 mol each of HA/A⁻ or 0.10 mol each at the same ratio?
Jawaban
The 1.0 mol pair; both have the same initial pH, but the larger amounts neutralize more added acid or base.
Kartu 377
Pertanyaan
For BHX(s) ⇌ BH⁺ + X⁻, why can raising pH increase the salt's solubility?
Jawaban
OH⁻ consumes BH⁺ to form B and H₂O, so dissolution shifts right to replace BH⁺. This is a qualitative prediction, not a pH-dependent solubility calculation.
Kartu 378
Pertanyaan
What does pH > pKa imply for a weak-acid pair?
Jawaban
The deprotonated form A⁻ predominates over HA.
Kartu 379
Pertanyaan
For HA + B ⇌ A⁻ + BH⁺, which side is favored when pKa(HA) = 4 and pKa(BH⁺) = 9?
Jawaban
Products are favored. Proton transfer moves toward the weaker acid–base pair, and K ≈ 10^(9 − 4) = 10^5.
Kartu 380
Pertanyaan
What is the pOH when [OH⁻] = 2.5 × 10^-4 M?
Jawaban
3.60, from -log(2.5 × 10^-4).
Kartu 381
Pertanyaan
What is the pH of 0.100 M HA when Ka = 1.0 × 10^-5?
Jawaban
About 3.00. The ICE setup gives Ka = x²/(0.100 − x); x ≈ 1.0 × 10^-3 M, and the 1.0% change validates the approximation.
Kartu 382
Pertanyaan
Why does a buffer fail after too much strong acid is added?
Jawaban
Its conjugate base is depleted, so added H⁺ is no longer consumed effectively.
Kartu 383
Pertanyaan
What do two clear equivalence regions on an acid titration curve suggest?
Jawaban
At least two distinguishable titratable protons; on a clean ideal curve with exactly two equivalence regions, this is consistent with a diprotic acid.
Kartu 384
Pertanyaan
A buffer has pKa 4.8 and [A⁻]/[HA] = 0.10; what is pH?
Jawaban
3.8, from 4.8 + log(0.10).
Kartu 385
Pertanyaan
Why is HCl stronger than HF in water despite F being more electronegative?
Jawaban
The H–F bond is much stronger; bond strength dominates this down-group binary-acid comparison.
Kartu 386
Pertanyaan
Why does percent ionization increase when a weak acid is diluted?
Jawaban
Dilution shifts ionization toward more particles, so a larger fraction ionizes even though [H₃O⁺] decreases.
Kartu 387
Pertanyaan
A buffer contains more HA than A⁻. Which addition can it neutralize in greater amount: strong acid or strong base?
Jawaban
Strong base. The larger HA reserve consumes more added OH⁻; a buffer with more A⁻ than HA instead has greater capacity for added strong acid.
Kartu 388
Pertanyaan
Why can removing a basic anion increase a salt's molar solubility without changing Ksp?
Jawaban
The equilibrium shifts to replace the consumed ion; Ksp remains fixed at the same temperature.
Kartu 389
Pertanyaan
Why can an acid–base indicator change color as pH changes?
Jawaban
Its protonated and deprotonated forms have different colors or other observable properties, and their relative amounts change with pH.
Kartu 390
Pertanyaan
What buffer results from mixing 1.0 mol HA with 0.40 mol OH⁻?
Jawaban
0.60 mol HA and 0.40 mol A⁻ remain, forming a buffer before any equilibrium calculation.
Kartu 391
Pertanyaan
What is the pH of 0.200 M weak base B when Kb = 2.0 × 10^-5 at 25°C?
Jawaban
About 11.30. The ICE setup gives Kb = x²/(0.200 − x); x ≈ 2.0 × 10^-3 M OH⁻, and the 1.0% change validates the approximation.
Kartu 392
Pertanyaan
Why does a weak acid alone not make an effective buffer?
Jawaban
It lacks a substantial conjugate-base reserve to consume added strong acid.
Kartu 393
Pertanyaan
What controls pH after excess strong base passes equivalence?
Jawaban
The concentration of excess OH⁻ after accounting for reaction stoichiometry and total volume.
Kartu 394
Pertanyaan
How should an indicator be chosen for a titration?
Jawaban
Its color-change range should fall within the steep pH change near the equivalence point.
Kartu 395
Pertanyaan
How can a measured pH and known pKa give a conjugate-base/acid ratio?
Jawaban
Rearrange Henderson–Hasselbalch: [A⁻]/[HA] = 10^(pH − pKa).
Kartu 396
Pertanyaan
Can a weak base and its conjugate acid form a buffer?
Jawaban
Yes, when both are present in significant amounts.
Kartu 397
Pertanyaan
For equal-volume buffers with the same conjugate-base/acid ratio, how does adding the same amount of strong acid affect a more concentrated versus less concentrated buffer?
Jawaban
The concentrated buffer changes pH less because it has greater capacity.
Kartu 398
Pertanyaan
How does equivalence-point pH compare for strong acid–strong base, weak acid–strong base, and weak base–strong acid titrations at 25°C?
Jawaban
Strong acid–strong base: pH 7.00. Weak acid–strong base: above 7.00 because the conjugate base reacts with water. Weak base–strong acid: below 7.00 because the conjugate acid reacts with water.
Kartu 399
Pertanyaan
Why should mole ratios replace concentration ratios after mixing buffer solutions?
Jawaban
Both components share the same final volume, so that volume cancels in [A⁻]/[HA].
Kartu 400
Pertanyaan
How does adding a little strong acid change a buffer's conjugate-base and conjugate-acid amounts?
Jawaban
The conjugate base decreases and its conjugate acid increases by the amount of strong acid consumed.
Kartu 401
Pertanyaan
What does entropy measure qualitatively?
Jawaban
The dispersal of matter and energy among available microstates.
Kartu 402
Pertanyaan
How is standard reaction entropy calculated?
Jawaban
ΔS°rxn = ΣνS°(products) − ΣνS°(reactants).
Kartu 403
Pertanyaan
What equation gives ΔG° from ΔH° and ΔS°, and what standard states do the degree symbols assume?
Jawaban
ΔG° = ΔH° − TΔS°. The standard states are pure substances, 1.0 M solutions, and gases at 1 atm or 1 bar; T is in kelvins and energy units must match.
Kartu 404
Pertanyaan
Does thermodynamic favorability guarantee a fast reaction?
Jawaban
No. A favorable reaction can be slow when its activation barrier is large.
Kartu 405
Pertanyaan
What is ΔG at equilibrium?
Jawaban
Zero under the current conditions because there is no net driving force.
Kartu 406
Pertanyaan
Why can an endothermic dissolution still be thermodynamically favorable?
Jawaban
A sufficiently positive entropy change can make TΔS exceed positive ΔH, giving negative ΔG.
Kartu 407
Pertanyaan
How can an unfavorable reaction be driven by a favorable one?
Jawaban
Couple them so their equations and ΔG values add to a negative overall ΔG.
Kartu 408
Pertanyaan
Where does oxidation occur in every electrochemical cell?
Jawaban
At the anode.
Kartu 409
Pertanyaan
How are standard cell potential and standard free energy related?
Jawaban
ΔG° = -nFE°cell.
Kartu 410
Pertanyaan
What equation gives cell potential under nonstandard conditions?
Jawaban
E = E° − (RT/nF) ln Q. When Q = 1, ln Q = 0, so E = E°.
Kartu 411
Pertanyaan
How is electrical charge related to current and time?
Jawaban
q = It.
Kartu 412
Pertanyaan
Which phase has greater molar entropy, liquid water or ice at the same temperature?
Jawaban
Liquid water because its molecules have more accessible arrangements and motion.
Kartu 413
Pertanyaan
Do elements in their standard states have zero standard molar entropy?
Jawaban
No. Their ΔHf° is zero, but their absolute S° values are positive above 0 K.
Kartu 414
Pertanyaan
How do the four ΔH° and ΔS° sign combinations determine thermodynamic favorability across temperature?
Jawaban
ΔH° < 0 and ΔS° > 0 is favorable at every temperature; ΔH° > 0 and ΔS° < 0 is thermodynamically unfavored at every temperature. If both are positive, favorability requires high temperature; if both are negative, it requires low temperature.
Kartu 415
Pertanyaan
What does it indicate when a thermodynamically favored process does not occur at a measurable rate?
Jawaban
It is under kinetic control, commonly because of a high activation energy; no measurable reaction does not mean the system is at equilibrium.
Kartu 416
Pertanyaan
How are ΔG° and K related?
Jawaban
ΔG° = -RT ln K.
Kartu 417
Pertanyaan
What two contributions compete in dissolving an ionic solid?
Jawaban
Enthalpy changes from separating and solvating particles, and entropy changes from their new dispersal and solvent organization.
Kartu 418
Pertanyaan
What must cancel when coupled reactions are added?
Jawaban
Shared intermediates, leaving the desired net reaction.
Kartu 419
Pertanyaan
Where does reduction occur in every electrochemical cell?
Jawaban
At the cathode.
Kartu 420
Pertanyaan
What sign of E°cell indicates a favorable standard galvanic reaction?
Jawaban
Positive E°cell, corresponding to negative ΔG°.
Kartu 421
Pertanyaan
If Q increases for a galvanic reaction, how does E change at fixed temperature?
Jawaban
E decreases according to the Nernst equation. Le Châtelier's principle does not apply to an operating cell away from equilibrium; use Q and Nernst reasoning instead.
Kartu 422
Pertanyaan
How are moles of electrons found from charge?
Jawaban
Moles e⁻ = q/F, where F ≈ 96485 C mol^-1 e⁻.
Kartu 423
Pertanyaan
How does producing more gas particles usually affect system entropy?
Jawaban
It increases entropy because the particles have more positional microstates.
Kartu 424
Pertanyaan
Can a dissolution with negative ΔH be unfavorable?
Jawaban
Yes. A sufficiently negative entropy change at the stated temperature can make ΔG positive.
Kartu 425
Pertanyaan
When can a process with ΔH > 0 and ΔS > 0 become favorable?
Jawaban
At sufficiently high temperature, when TΔS exceeds ΔH.
Kartu 426
Pertanyaan
How does a catalyst affect ΔG?
Jawaban
It does not change ΔG; it lowers the activation barrier for both directions.
Kartu 427
Pertanyaan
For A → B, ΔGf°(A) = -50 kJ mol^-1 and ΔGf°(B) = -80 kJ mol^-1. What is ΔG°rxn?
Jawaban
-30 kJ mol^-1. Use ΣνΔGf°(products) − ΣνΔGf°(reactants) = -80 − (-50).
Kartu 428
Pertanyaan
Why can dissolving a gas in a liquid have a negative entropy change?
Jawaban
Gas particles lose much of their translational freedom when confined and solvated in the liquid.
Kartu 429
Pertanyaan
If coupled steps have ΔG values +20 kJ and -35 kJ, what is overall ΔG?
Jawaban
-15 kJ, so the combined process is thermodynamically favorable under those conditions.
Kartu 430
Pertanyaan
What role does each half-cell solution play in an electrochemical cell?
Jawaban
It supplies dissolved redox species at an electrode interface and carries ions within its compartment. Separate compartments prevent direct mixing while the external circuit and salt bridge connect the half-cells.
Kartu 431
Pertanyaan
How is E°cell found from standard reduction potentials?
Jawaban
E°cell = E°cathode − E°anode, using both tabulated values as reductions.
Kartu 432
Pertanyaan
How does a cell's potential magnitude change as Q approaches or moves away from K, and what is E at equilibrium?
Jawaban
|E| falls toward zero as Q approaches K and grows as the system moves farther from equilibrium. At equilibrium, Q = K and E = 0.
Kartu 433
Pertanyaan
How many moles of electrons pass when 1.93 × 10^5 C flows?
Jawaban
2.00 mol e⁻, from q/F.
Kartu 434
Pertanyaan
How does a salt bridge maintain charge balance in a galvanic cell?
Jawaban
Anions migrate toward the anode compartment and cations toward the cathode compartment, countering the net charge imbalances created by the two half-reactions.
Kartu 435
Pertanyaan
Why does raising a substance's temperature generally increase its entropy?
Jawaban
Energy spreads across more accessible particle energy states, increasing the number of possible microscopic arrangements.
Kartu 436
Pertanyaan
When can a process with ΔH < 0 and ΔS < 0 be favorable?
Jawaban
At sufficiently low temperature, where the unfavorable -TΔS term is small.
Kartu 437
Pertanyaan
Why can diamond persist even though graphite is more stable at standard conditions?
Jawaban
Conversion has a large activation barrier, so diamond is kinetically persistent.
Kartu 438
Pertanyaan
What do the external circuit and measuring device do in an electrochemical cell?
Jawaban
The circuit carries electrons from anode to cathode; a voltmeter measures potential difference, while an ammeter in series measures current.
Kartu 439
Pertanyaan
At constant temperature, how does increasing the volume available to a gas affect its entropy?
Jawaban
Entropy increases because the gas particles can occupy more positions in the larger space, so more microstates are accessible.
Kartu 440
Pertanyaan
How does reversing one coupled reaction affect its ΔG?
Jawaban
It reverses the sign of that reaction's ΔG.
Kartu 441
Pertanyaan
Why is n required in ΔG° = -nFE°?
Jawaban
It is the moles of electrons transferred per balanced reaction, linking charge flow to reaction extent.
Kartu 442
Pertanyaan
What makes an electrolytic cell operate?
Jawaban
An external power source drives a thermodynamically unfavorable redox reaction; oxidation still occurs at the anode and reduction at the cathode.
Kartu 443
Pertanyaan
In an Mⁿ⁺/M concentration cell, which half-cell is the anode: the dilute or concentrated ion solution?
Jawaban
The dilute half-cell. Oxidation produces Mⁿ⁺ there, while reduction consumes Mⁿ⁺ in the concentrated half-cell, so electrons flow from dilute to concentrated as the concentrations move toward equality.
Kartu 444
Pertanyaan
How is deposited metal mass found from current and time?
Jawaban
Find q = It, convert q/F to moles e⁻, use the half-reaction ratio to moles metal, then multiply by molar mass.
Kartu 445
Pertanyaan
Given product S° total 500 J mol^-1 K^-1 and reactant total 420 J mol^-1 K^-1, what is ΔS°?
Jawaban
+80 J mol^-1 K^-1.
Kartu 446
Pertanyaan
How do electrode masses change in a Zn–Cu galvanic cell?
Jawaban
The Zn anode loses mass as Zn → Zn²⁺ + 2e⁻, while the Cu cathode gains mass as Cu²⁺ + 2e⁻ → Cu.
Kartu 447
Pertanyaan
What is ΔG° when ΔH° = 50 kJ mol^-1, ΔS° = 0.200 kJ mol^-1 K^-1, and T = 300 K?
Jawaban
-10 kJ mol^-1, from ΔG° = 50 − (300)(0.200).
Kartu 448
Pertanyaan
Why can temperature change a solid's solubility?
Jawaban
Temperature changes the balance of ΔH and TΔS, so it changes the free energy of dissolution and the equilibrium constant.
Kartu 449
Pertanyaan
What does the size of ΔG° relative to RT imply about K?
Jawaban
ΔG° near zero gives K near 1. When |ΔG°| is much larger than RT, K is far from 1: negative ΔG° gives K ≫ 1, while positive ΔG° gives K ≪ 1.
Kartu 450
Pertanyaan
Bubbles form at an inert cathode in acidic solution; which half-reaction can explain them?
Jawaban
2H⁺ + 2e⁻ → H₂(g). Gas evolution at the cathode can be direct evidence of reduction.
450 kartu
AP Chemistry Flashcards: Complete 9-Unit Course Review
Nibomo akan terbuka agar Anda bisa mulai belajar.