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