MCAT Physics & Chemistry Equation Flashcards: Formulas, Units & When to Use Them

Kartu dalam dek ini

1. Kartu 1

   Pertanyaan

   Which relationship gives average velocity over a time interval?

   Jawaban

   $\bar v=\Delta x/\Delta t$.

   Displacement $\Delta x$ includes direction; average speed instead uses total distance.

2. Kartu 2

   Pertanyaan

   How do you convert a sample's mass to moles?

   Jawaban

   $n=m/M$.

   Divide mass $m$ by molar mass $M$ using compatible units.

3. Kartu 3

   Pertanyaan

   What is the electrostatic force between two point charges?

   Jawaban

   $F=k_e|q_1q_2|/r^2$.

   It acts along the line joining the charges; like charges repel and unlike charges attract.

4. Kartu 4

   Pertanyaan

   How is pH defined from hydrogen-ion activity in the usual MCAT approximation?

   Jawaban

   $\mathrm{pH}=-\log[H^+]$.

   The bracket approximation uses molar concentration for sufficiently dilute solutions.

5. Kartu 5

   Pertanyaan

   How are period and frequency related?

   Jawaban

   $f=1/T$.

   Frequency is in hertz and period is in seconds.

6. Kartu 6

   Pertanyaan

   Which relationship gives sensible heat for a sample with known specific heat?

   Jawaban

   $q=mc\Delta T$.

   Use it within one phase when the specific heat $c$ is approximately constant.

7. Kartu 7

   Pertanyaan

   Which relationship defines mass density?

   Jawaban

   $\rho=m/V$.

   Density has SI units of $\mathrm{kg/m^3}$; $1\ \mathrm{g/mL}=1000\ \mathrm{kg/m^3}$.

8. Kartu 8

   Pertanyaan

   What is the concentration equilibrium constant for $aA+bB\rightleftharpoons cC+dD$?

   Jawaban

   $K_c=[C]^c[D]^d/([A]^a[B]^b)$.

   Use equilibrium concentrations and stoichiometric coefficients as exponents.

9. Kartu 9

   Pertanyaan

   How is photon energy related to frequency and wavelength?

   Jawaban

   $E=hf=hc/\lambda$.

   Higher frequency and shorter wavelength mean greater photon energy.

10. Kartu 10

    Pertanyaan

    How is standard cell potential calculated from reduction potentials?

    Jawaban

    $E^\circ_{\mathrm{cell}}=E^\circ_{\mathrm{cathode}}-E^\circ_{\mathrm{anode}}$.

    Use both tabulated values as reductions; do not multiply potentials by stoichiometric coefficients.

11. Kartu 11

    Pertanyaan

    Which SI base units cover the quantities most often used in MCAT mechanics and circuits?

    Jawaban

    Use meters (m) for length, kilograms (kg) for mass, seconds (s) for time, and amperes (A) for electric current. Amount of substance uses moles (mol), and thermodynamic temperature uses kelvin (K).

12. Kartu 12

    Pertanyaan

    How do you convert Celsius temperature to kelvin for gas-law work?

    Jawaban

    $T_K=T_{^\circ C}+273.15$.

    Gas-law temperatures must be absolute; a Celsius value cannot be inserted directly.

13. Kartu 13

    Pertanyaan

    Which relationship gives average acceleration over a time interval?

    Jawaban

    $\bar a=\Delta v/\Delta t$.

    Acceleration has SI units of $\mathrm{m/s^2}$.

14. Kartu 14

    Pertanyaan

    How is reaction rate related to a species concentration and its stoichiometric coefficient?

    Jawaban

    For $aA\rightarrow cC$, $\mathrm{rate}=-(1/a)d[A]/dt=(1/c)d[C]/dt$.

    The signs and coefficients make one reaction rate consistent across species.

15. Kartu 15

    Pertanyaan

    What electric-field magnitude does a point charge produce?

    Jawaban

    $E=k_e|q|/r^2$.

    The field points away from a positive source charge and toward a negative one.

16. Kartu 16

    Pertanyaan

    How do moles relate to the number of microscopic particles?

    Jawaban

    $N=nN_A$, with $N_A\approx6.022\times10^{23}\ \mathrm{mol^{-1}}$.

17. Kartu 17

    Pertanyaan

    For constant acceleration, how does velocity change with time?

    Jawaban

    $v=v_0+at$.

    Use it when acceleration is constant and the elapsed time is known.

18. Kartu 18

    Pertanyaan

    How is pOH defined?

    Jawaban

    $\mathrm{pOH}=-\log[OH^-]$.

19. Kartu 19

    Pertanyaan

    How is specific gravity defined?

    Jawaban

    $SG=\rho_{\mathrm{substance}}/\rho_{\mathrm{water}}$.

    It is dimensionless because it is a density ratio.

20. Kartu 20

    Pertanyaan

    How is an object's heat capacity related to heat and temperature change?

    Jawaban

    $q=C\Delta T$.

    Heat capacity $C$ applies to the whole object; specific heat is per unit mass.

21. Kartu 21

    Pertanyaan

    How are frequency and wavelength related for electromagnetic radiation in vacuum?

    Jawaban

    $c=f\lambda$.

    Use $c\approx3.00\times10^8\ \mathrm{m/s}$.

22. Kartu 22

    Pertanyaan

    Which species are omitted from a heterogeneous equilibrium expression?

    Jawaban

    Pure solids and pure liquids are omitted because their activities are effectively constant. Gases and dissolved species remain.

23. Kartu 23

    Pertanyaan

    What force does an electric field exert on a charge?

    Jawaban

    $\vec F=q\vec E$.

    A negative charge feels force opposite the field direction.

24. Kartu 24

    Pertanyaan

    Which equation relates pressure, volume, amount, and temperature for an ideal gas?

    Jawaban

    $PV=nRT$.

    Use absolute temperature and a gas constant whose units match pressure and volume.

25. Kartu 25

    Pertanyaan

    Which equation relates wave speed, frequency, and wavelength?

    Jawaban

    $v=f\lambda$.

    The medium sets the wave speed; changing frequency then changes wavelength.

26. Kartu 26

    Pertanyaan

    What is the water-ion product at $25^\circ\mathrm{C}$?

    Jawaban

    $K_w=[H^+][OH^-]\approx1.0\times10^{-14}$.

    Its value changes with temperature.

27. Kartu 27

    Pertanyaan

    What base-unit dimensions define one newton?

    Jawaban

    $1\ \mathrm{N}=1\ \mathrm{kg\,m\,s^{-2}}$.

    A force must have dimensions of mass times acceleration.

28. Kartu 28

    Pertanyaan

    How is cell potential related to reaction free energy?

    Jawaban

    $\Delta G=-nFE_{\mathrm{cell}}$.

    A positive galvanic-cell potential gives negative $\Delta G$ for the written reaction.

29. Kartu 29

    Pertanyaan

    For constant acceleration, how does displacement depend on time?

    Jawaban

    $\Delta x=v_0t+\tfrac12at^2$.

    Choose a positive direction first, then keep signs consistent.

30. Kartu 30

    Pertanyaan

    How is molarity defined?

    Jawaban

    $M=n_{\mathrm{solute}}/V_{\mathrm{solution}}$.

    Use solution volume in liters, so molarity has units of $\mathrm{mol/L}$.

31. Kartu 31

    Pertanyaan

    What electric potential does a point charge produce?

    Jawaban

    $V=k_e q/r$.

    Potential is scalar, so contributions from multiple charges add algebraically.

32. Kartu 32

    Pertanyaan

    Which relationship gives heat absorbed or released during a phase change?

    Jawaban

    $q=n\Delta H_{\mathrm{phase}}$, or $q=mL$ when latent heat is given per unit mass. Temperature stays constant during an ideal equilibrium phase change.

33. Kartu 33

    Pertanyaan

    Which constant-acceleration equation avoids time?

    Jawaban

    $v^2=v_0^2+2a\Delta x$.

    It connects speed and displacement when time is absent.

34. Kartu 34

    Pertanyaan

    What is the general experimental rate-law form?

    Jawaban

    $\mathrm{rate}=k[A]^m[B]^n$.

    The exponents are determined experimentally and need not equal overall-reaction coefficients.

35. Kartu 35

    Pertanyaan

    Which relationship defines pressure from a normal force?

    Jawaban

    $P=F_\perp/A$.

    Pressure is scalar and measured in pascals.

36. Kartu 36

    Pertanyaan

    What pH–pOH relationship applies at $25^\circ\mathrm{C}$?

    Jawaban

    $\mathrm{pH}+\mathrm{pOH}=14.00$.

    More generally, $\mathrm{pH}+\mathrm{pOH}=\mathrm{p}K_w$.

37. Kartu 37

    Pertanyaan

    How is wave intensity related to transmitted power and area?

    Jawaban

    $I=P/A$.

    Intensity is power per area, measured in $\mathrm{W/m^2}$.

38. Kartu 38

    Pertanyaan

    How is molality defined?

    Jawaban

    $m=n_{\mathrm{solute}}/(\mathrm{kg\ of\ solvent})$.

    Molality uses solvent mass, not solution volume, and is temperature-independent.

39. Kartu 39

    Pertanyaan

    What base-unit dimensions define one joule?

    Jawaban

    $1\ \mathrm{J}=1\ \mathrm{N\,m}=1\ \mathrm{kg\,m^2\,s^{-2}}$.

    Work, energy, and heat share this unit.

40. Kartu 40

    Pertanyaan

    What is the chemistry sign-convention form of the first law?

    Jawaban

    $\Delta U=q+w$.

    $q>0$ means heat enters the system, and $w>0$ means work is done on the system.

41. Kartu 41

    Pertanyaan

    How is refractive index related to light speed in a medium?

    Jawaban

    $n=c/v$.

    A larger refractive index means a lower phase speed in the material.

42. Kartu 42

    Pertanyaan

    What equation links net force and acceleration?

    Jawaban

    $\sum \vec F=m\vec a$.

    The vector sum of external forces determines the acceleration.

43. Kartu 43

    Pertanyaan

    Which relationship compares two states of a fixed amount of ideal gas?

    Jawaban

    $P_1V_1/T_1=P_2V_2/T_2$.

    It assumes the amount of gas is unchanged. Holding one variable constant gives Boyle's, Charles's, or Gay-Lussac's law.

44. Kartu 44

    Pertanyaan

    How is electric potential energy related to charge and voltage?

    Jawaban

    $\Delta U=q\Delta V$.

    A positive charge gains potential energy when moved to higher potential; a negative charge does the opposite.

45. Kartu 45

    Pertanyaan

    How are standard cell potential and the equilibrium constant related?

    Jawaban

    $\ln K=nFE^\circ_{\mathrm{cell}}/(RT)$.

    At equilibrium, the Nernst equation gives $E_{\mathrm{cell}}=0$.

46. Kartu 46

    Pertanyaan

    What is an object's weight near Earth's surface?

    Jawaban

    $W=mg$.

    Weight is a force in newtons; mass remains in kilograms.

47. Kartu 47

    Pertanyaan

    How are $K_p$ and $K_c$ related for an ideal-gas reaction?

    Jawaban

    $K_p=K_c(RT)^{\Delta n_{\mathrm{gas}}}$.

    $\Delta n_{\mathrm{gas}}$ is gaseous product coefficients minus gaseous reactant coefficients.

48. Kartu 48

    Pertanyaan

    How does pressure change with depth in a static incompressible fluid?

    Jawaban

    $P=P_0+\rho gh$.

    $h$ is depth below the surface; the gauge pressure is $\rho gh$.

49. Kartu 49

    Pertanyaan

    How do the units of a rate constant depend on overall reaction order $N$?

    Jawaban

    $[k]=\mathrm{M^{1-N}s^{-1}}$ when rate is in $\mathrm{M/s}$. For example, first-order $k$ has units of $\mathrm{s^{-1}}$.

50. Kartu 50

    Pertanyaan

    Which relationship defines electric current?

    Jawaban

    $I=\Delta Q/\Delta t$.

    Conventional current points in the direction positive charge would move.

51. Kartu 51

    Pertanyaan

    What is the acid-dissociation expression for $HA\rightleftharpoons H^++A^-$?

    Jawaban

    $K_a=[H^+][A^-]/[HA]$.

    A larger $K_a$ means a stronger acid under comparable conditions.

52. Kartu 52

    Pertanyaan

    What equation governs refraction at a boundary?

    Jawaban

    $n_1\sin\theta_1=n_2\sin\theta_2$.

    Angles are measured from the normal, not the surface.

53. Kartu 53

    Pertanyaan

    How is mole fraction defined for component $i$?

    Jawaban

    $X_i=n_i/\sum_jn_j$.

    Mole fractions are dimensionless and sum to 1.

54. Kartu 54

    Pertanyaan

    What SI units and base dimensions define pressure?

    Jawaban

    Pressure is measured in pascals: $1\ \mathrm{Pa}=1\ \mathrm{N/m^2}=1\ \mathrm{kg\,m^{-1}\,s^{-2}}$.

55. Kartu 55

    Pertanyaan

    What pressure–volume work occurs against constant external pressure?

    Jawaban

    $w=-P_{\mathrm{ext}}\Delta V$.

    Expansion has $\Delta V>0$ and therefore negative work on the system.

56. Kartu 56

    Pertanyaan

    How does intensity from an isotropic point source vary with distance?

    Jawaban

    $I=P/(4\pi r^2)$.

    Doubling distance reduces intensity to one quarter if absorption is negligible.

57. Kartu 57

    Pertanyaan

    How large can static friction become before slipping begins?

    Jawaban

    $f_s\leq\mu_sN$, with $f_{s,\max}=\mu_sN$.

    Static friction matches the needed opposing force up to its maximum; it isn't always equal to $\mu_sN$.

58. Kartu 58

    Pertanyaan

    Which relationship handles dilution when solute amount is conserved?

    Jawaban

    $M_1V_1=M_2V_2$.

    It applies when solvent is added without reaction or solute loss.

59. Kartu 59

    Pertanyaan

    What is Ohm's law for an ohmic element?

    Jawaban

    $V=IR$.

    It applies when resistance is approximately constant over the operating range.

60. Kartu 60

    Pertanyaan

    How is the reaction quotient $Q$ constructed?

    Jawaban

    Use the same expression as $K$, but insert the current—not necessarily equilibrium—activities or concentrations.

61. Kartu 61

    Pertanyaan

    What is the usual model for kinetic friction on a sliding surface?

    Jawaban

    $f_k=\mu_kN$.

    The force points opposite the relative sliding motion.

62. Kartu 62

    Pertanyaan

    What is the base-dissociation expression for $B+H_2O\rightleftharpoons HB^++OH^-$?

    Jawaban

    $K_b=[HB^+][OH^-]/[B]$.

63. Kartu 63

    Pertanyaan

    What equation expresses Pascal's principle in a hydraulic device?

    Jawaban

    $F_1/A_1=F_2/A_2$.

    An applied pressure change is transmitted through a confined incompressible fluid.

64. Kartu 64

    Pertanyaan

    How much charge passes through a cell carrying constant current?

    Jawaban

    $Q=It$.

    Use amperes and seconds to obtain coulombs.

65. Kartu 65

    Pertanyaan

    What is the critical-angle condition for total internal reflection?

    Jawaban

    $\sin\theta_c=n_2/n_1$ when $n_1>n_2$.

    Total internal reflection occurs only when light starts in the higher-index medium and $\theta_1>\theta_c$.

66. Kartu 66

    Pertanyaan

    How is total pressure related to component pressures in an ideal gas mixture?

    Jawaban

    $P_{\mathrm{tot}}=\sum_iP_i$.

    Dalton's law treats each gas as contributing its own partial pressure.

67. Kartu 67

    Pertanyaan

    How is the coulomb expressed through SI base units?

    Jawaban

    $1\ \mathrm{C}=1\ \mathrm{A\,s}$.

    Charge equals current multiplied by time.

68. Kartu 68

    Pertanyaan

    How is standard reaction enthalpy obtained from standard formation enthalpies?

    Jawaban

    $\Delta H^\circ_{\mathrm{rxn}}=\sum\nu\Delta H_f^\circ(\mathrm{products})-\sum\nu\Delta H_f^\circ(\mathrm{reactants})$.

69. Kartu 69

    Pertanyaan

    How is sound intensity level in decibels defined?

    Jawaban

    $\beta=10\log_{10}(I/I_0)$.

    The reference intensity is commonly $I_0=10^{-12}\ \mathrm{W/m^2}$.

70. Kartu 70

    Pertanyaan

    What is the integrated rate law for a zero-order reactant?

    Jawaban

    $[A]_t=[A]_0-kt$.

    A plot of $[A]$ versus time is linear with slope $-k$.

71. Kartu 71

    Pertanyaan

    How does a uniform wire's resistance depend on material and geometry?

    Jawaban

    $R=\rho L/A$.

    Longer wires have more resistance; larger cross-sectional area lowers it. Here $\rho$ is resistivity.

72. Kartu 72

    Pertanyaan

    Which equation gives the magnitude of torque from a force?

    Jawaban

    $\tau=rF\sin\theta=r_\perp F$.

    Here $r_\perp$ is the perpendicular lever arm from the pivot to the force's line of action.

73. Kartu 73

    Pertanyaan

    How is mass percent composition calculated?

    Jawaban

    $\%\mathrm{\ by\ mass}=100\times m_{\mathrm{component}}/m_{\mathrm{total}}$.

74. Kartu 74

    Pertanyaan

    What buoyant force acts on a submerged object?

    Jawaban

    $F_B=\rho_{\mathrm{fluid}}V_{\mathrm{displaced}}g$.

    It equals the weight of displaced fluid.

75. Kartu 75

    Pertanyaan

    How is $\mathrm{p}K_a$ related to $K_a$?

    Jawaban

    $\mathrm{p}K_a=-\log K_a$.

    Lower $\mathrm{p}K_a$ corresponds to the stronger acid.

76. Kartu 76

    Pertanyaan

    What two conditions define static mechanical equilibrium?

    Jawaban

    $\sum \vec F=0$ and $\sum\tau=0$.

    Both translational and rotational equilibrium are required.

77. Kartu 77

    Pertanyaan

    How does Hess's law combine reaction enthalpies?

    Jawaban

    Add the manipulated step equations and add their $\Delta H$ values. Reversing a step changes the sign; multiplying a step multiplies $\Delta H$ by the same factor.

78. Kartu 78

    Pertanyaan

    Which equivalent forms give electrical power in a resistor?

    Jawaban

    $P=IV=I^2R=V^2/R$.

    Choose the form that uses the known current, voltage, and resistance.

79. Kartu 79

    Pertanyaan

    How does mole fraction determine an ideal gas's partial pressure?

    Jawaban

    $P_i=X_iP_{\mathrm{tot}}$, where $X_i=n_i/n_{\mathrm{tot}}$.

80. Kartu 80

    Pertanyaan

    What decibel change corresponds to multiplying sound intensity by 10?

    Jawaban

    A tenfold intensity increase adds $10\ \mathrm{dB}$ because $10\log_{10}(10)=10$. A hundredfold increase adds $20\ \mathrm{dB}$.

81. Kartu 81

    Pertanyaan

    How does comparing $Q$ with $K$ predict reaction direction?

    Jawaban

    If $Q<K$, the forward direction is favored. If $Q>K$, the reverse direction is favored. If $Q=K$, the system is at equilibrium.

82. Kartu 82

    Pertanyaan

    Which equation relates object, image, and focal distances for a thin lens or spherical mirror?

    Jawaban

    $1/f=1/d_o+1/d_i$.

    Use the adopted sign convention consistently; positive $d_i$ usually denotes a real image.

83. Kartu 83

    Pertanyaan

    How do charge and Faraday's constant give moles of electrons?

    Jawaban

    $n_{e^-}=Q/F$, where $F\approx9.6485\times10^4\ \mathrm{C/mol\ e^-}$.

84. Kartu 84

    Pertanyaan

    How is the volt expressed through joules and coulombs?

    Jawaban

    $1\ \mathrm{V}=1\ \mathrm{J/C}$.

    Voltage is energy transferred per unit charge.

85. Kartu 85

    Pertanyaan

    How is $\mathrm{p}K_b$ related to $K_b$?

    Jawaban

    $\mathrm{p}K_b=-\log K_b$.

86. Kartu 86

    Pertanyaan

    What work is done by a constant force through a displacement?

    Jawaban

    $W=Fd\cos\theta$.

    $\theta$ is the angle between the force and displacement; perpendicular force does zero work.

87. Kartu 87

    Pertanyaan

    How is volume percent calculated for a liquid mixture?

    Jawaban

    $\%\mathrm{\ by\ volume}=100\times V_{\mathrm{component}}/V_{\mathrm{solution}}$.

    Use it only when the problem defines composition by volume.

88. Kartu 88

    Pertanyaan

    How do resistors combine in series?

    Jawaban

    $R_{\mathrm{eq}}=\sum_iR_i$.

    Series elements carry the same current and their voltage drops add.

89. Kartu 89

    Pertanyaan

    What is the half-life of a zero-order reactant?

    Jawaban

    $t_{1/2}=[A]_0/(2k)$.

    Unlike first-order half-life, it depends on starting concentration.

90. Kartu 90

    Pertanyaan

    How is volumetric flow rate related to cross-sectional area and speed?

    Jawaban

    $Q=Av$.

    $Q$ has SI units of $\mathrm{m^3/s}$ and assumes the average speed across the section.

    

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91. Kartu 91

    Pertanyaan

    How can average bond energies estimate reaction enthalpy?

    Jawaban

    $\Delta H_{\mathrm{rxn}}\approx\sum D(\mathrm{bonds\ broken})-\sum D(\mathrm{bonds\ formed})$.

    Breaking bonds costs energy; forming bonds releases it.

92. Kartu 92

    Pertanyaan

    What is the translational kinetic energy of a point mass?

    Jawaban

    $K=\tfrac12mv^2$.

    Kinetic energy is a scalar measured in joules.

93. Kartu 93

    Pertanyaan

    What ratio defines parts per million by mass?

    Jawaban

    $\mathrm{ppm}=10^6\times m_{\mathrm{solute}}/m_{\mathrm{solution}}$.

    For dilute aqueous solutions, $1\ \mathrm{ppm}$ is often approximately $1\ \mathrm{mg/L}$ when density is near $1\ \mathrm{kg/L}$.

94. Kartu 94

    Pertanyaan

    How do resistors combine in parallel?

    Jawaban

    $1/R_{\mathrm{eq}}=\sum_i1/R_i$.

    Parallel branches share the same voltage, and the equivalent resistance is below the smallest branch resistance.

95. Kartu 95

    Pertanyaan

    How are the dissociation constants of a conjugate acid–base pair related?

    Jawaban

    $K_aK_b=K_w$.

    At $25^\circ\mathrm{C}$, $\mathrm{p}K_a+\mathrm{p}K_b=14.00$.

96. Kartu 96

    Pertanyaan

    How do powers of ten combine when multiplying quantities in scientific notation?

    Jawaban

    Multiply the coefficients and add the exponents: $(a\times10^m)(b\times10^n)=ab\times10^{m+n}$. Then normalize the result so its final coefficient $c$ satisfies $1\leq|c|<10$; a coefficient of exactly 10 becomes 1 while the exponent increases by 1.

97. Kartu 97

    Pertanyaan

    How many moles of a product requiring $z$ electrons per mole form during electrolysis?

    Jawaban

    $n_{\mathrm{product}}=Q/(zF)=It/(zF)$.

    This is the ideal Faraday-law result before any stated efficiency correction.

98. Kartu 98

    Pertanyaan

    How is lateral magnification related to image and object distances?

    Jawaban

    $m=h_i/h_o=-d_i/d_o$.

    A negative magnification indicates inversion; $|m|$ gives the size ratio.

99. Kartu 99

    Pertanyaan

    What is the average translational kinetic energy per mole of an ideal gas?

    Jawaban

    $\overline{K}=\tfrac32RT$.

    It depends only on absolute temperature, not molecular identity.

100. Kartu 100

     Pertanyaan

     What are the allowed frequencies of a string fixed at both ends?

     Jawaban

     $f_n=nv/(2L)$ for $n=1,2,3,\ldots$.

     Both ends are nodes, so every positive integer harmonic is allowed.

101. Kartu 101

     Pertanyaan

     How does reversing a reaction change its equilibrium constant?

     Jawaban

     $K_{\mathrm{reverse}}=1/K_{\mathrm{forward}}$.

102. Kartu 102

     Pertanyaan

     What does the work–energy theorem say?

     Jawaban

     $W_{\mathrm{net}}=\Delta K$.

     Net work changes kinetic energy, even when individual forces are nonconservative.

103. Kartu 103

     Pertanyaan

     What entropy change accompanies reversible heat transfer at constant temperature?

     Jawaban

     $\Delta S=q_{\mathrm{rev}}/T$.

     Temperature must be in kelvin.

104. Kartu 104

     Pertanyaan

     What does Kirchhoff's junction rule require?

     Jawaban

     $\sum I_{\mathrm{in}}=\sum I_{\mathrm{out}}$.

     It follows from conservation of charge at a node.

105. Kartu 105

     Pertanyaan

     Which equation estimates the pH of a buffer made from a weak acid and its conjugate base?

     Jawaban

     $\mathrm{pH}=\mathrm{p}K_a+\log([A^-]/[HA])$.

     Henderson–Hasselbalch works best when both buffer components are present in meaningful amounts.

106. Kartu 106

     Pertanyaan

     What continuity relationship applies to steady incompressible flow?

     Jawaban

     $A_1v_1=A_2v_2$.

     A narrower section has a larger average speed when the same volume passes each second.

107. Kartu 107

     Pertanyaan

     A liquid has known density and volume. Which rearranged density relationship gives its mass?

     Jawaban

     $m=\rho V$.

     Here $m$ is mass, $\rho$ is density, and $V$ is volume; use compatible units when density and volume are known. For example, $25\ \mathrm{mL}$ of a $1.20\ \mathrm{g/mL}$ solution has mass $m=(1.20)(25)=30\ \mathrm{g}$.

108. Kartu 108

     Pertanyaan

     What is local gravitational potential energy near Earth's surface?

     Jawaban

     $U_g=mgh$.

     Only changes matter: $\Delta U_g=mg\Delta h$ when $g$ is approximately constant.

109. Kartu 109

     Pertanyaan

     What is the integrated rate law for a first-order reactant?

     Jawaban

     $\ln[A]_t=\ln[A]_0-kt$.

     A plot of $\ln[A]$ versus time is linear with slope $-k$.

110. Kartu 110

     Pertanyaan

     What are the allowed frequencies of a pipe open at both ends?

     Jawaban

     $f_n=nv/(2L)$ for $n=1,2,3,\ldots$.

     Both open ends are displacement antinodes.

111. Kartu 111

     Pertanyaan

     Which equation relates Gibbs free energy, enthalpy, and entropy at constant temperature?

     Jawaban

     $\Delta G=\Delta H-T\Delta S$.

     Use compatible energy units and absolute temperature.

112. Kartu 112

     Pertanyaan

     What does Kirchhoff's loop rule require?

     Jawaban

     $\sum\Delta V=0$ around any closed loop.

     Voltage rises and drops must be assigned consistently with the chosen traversal direction.

113. Kartu 113

     Pertanyaan

     What elastic potential energy is stored in an ideal spring?

     Jawaban

     $U_s=\tfrac12kx^2$.

     $x$ is displacement from equilibrium and $k$ has units of $\mathrm{N/m}$.

114. Kartu 114

     Pertanyaan

     How does multiplying every reaction coefficient by a factor $n$ change $K$?

     Jawaban

     $K_{\mathrm{new}}=K^n$.

     Dividing coefficients by $n$ takes the corresponding root.

115. Kartu 115

     Pertanyaan

     How can you estimate the order of magnitude of a quotient without a calculator?

     Jawaban

     Divide the leading coefficients and subtract powers of ten: $(a\times10^m)/(b\times10^n)=(a/b)\times10^{m-n}$. Normalize the result so its final coefficient $c$ satisfies $1\leq|c|<10$; if the coefficient is exactly 10, write it as 1 and increase the exponent by 1.

116. Kartu 116

     Pertanyaan

     How is lens power related to focal length?

     Jawaban

     $P=1/f$ with $f$ in meters.

     Power is measured in diopters; converging lenses have positive power and diverging lenses negative power.

117. Kartu 117

     Pertanyaan

     How does root-mean-square molecular speed depend on molar mass?

     Jawaban

     $v_{\mathrm{rms}}=\sqrt{3RT/M}$.

     Use molar mass $M$ in $\mathrm{kg/mol}$; lighter gases move faster at the same temperature.

118. Kartu 118

     Pertanyaan

     Which equation relates pressure, speed, and height along ideal fluid flow?

     Jawaban

     $P+\tfrac12\rho v^2+\rho gy=\text{constant}$.

     Bernoulli's equation assumes steady, incompressible, nonviscous flow along a streamline.

119. Kartu 119

     Pertanyaan

     What is the Nernst equation for a cell reaction?

     Jawaban

     $E=E^\circ-(RT/(nF))\ln Q$.

     At $25^\circ\mathrm{C}$, $E=E^\circ-(0.0592\ \mathrm{V}/n)\log Q$.

120. Kartu 120

     Pertanyaan

     What force does an ideal spring exert?

     Jawaban

     $F_s=-kx$.

     The minus sign means the spring force points back toward equilibrium.

121. Kartu 121

     Pertanyaan

     What conjugate-base-to-acid ratio gives a target buffer pH?

     Jawaban

     $[A^-]/[HA]=10^{\mathrm{pH}-\mathrm{p}K_a}$.

     This is Henderson–Hasselbalch solved for the composition ratio.

122. Kartu 122

     Pertanyaan

     Which relationship defines capacitance?

     Jawaban

     $C=Q/V$.

     Capacitance is charge stored per potential difference and is measured in farads.

123. Kartu 123

     Pertanyaan

     How do elemental mass percentages lead to an empirical formula?

     Jawaban

     Convert each element's mass to moles, divide every mole amount by the smallest, then multiply to obtain the smallest whole-number ratio. The retrieval target is the mole ratio, not the mass ratio.

124. Kartu 124

     Pertanyaan

     When can mechanical energy be conserved?

     Jawaban

     $K_i+U_i=K_f+U_f$ when only conservative forces do work. With nonconservative work, use $W_{nc}=\Delta(K+U)$.

125. Kartu 125

     Pertanyaan

     What sign of $\Delta G$ indicates a thermodynamically spontaneous forward process at constant temperature and pressure?

     Jawaban

     $\Delta G<0$. At equilibrium $\Delta G=0$; $\Delta G>0$ favors the reverse direction. Spontaneity does not say the reaction is fast.

126. Kartu 126

     Pertanyaan

     Which metric-prefix factors correspond to milli-, micro-, and nano-?

     Jawaban

     Milli is $10^{-3}$, micro is $10^{-6}$, and nano is $10^{-9}$. Each step is a factor of $10^3$.

127. Kartu 127

     Pertanyaan

     What is the pH at the half-equivalence point of a weak-acid/strong-base titration?

     Jawaban

     $\mathrm{pH}=\mathrm{p}K_a$.

     Half of the original weak acid has become conjugate base, so $[A^-]=[HA]$.

128. Kartu 128

     Pertanyaan

     What are the allowed frequencies of a pipe closed at one end?

     Jawaban

     $f_n=nv/(4L)$ for odd $n=1,3,5,\ldots$.

     The closed end is a displacement node and the open end is an antinode.

129. Kartu 129

     Pertanyaan

     What is the half-life of a first-order reaction?

     Jawaban

     $t_{1/2}=\ln2/k$.

     It is independent of initial concentration.

130. Kartu 130

     Pertanyaan

     How is the focal length of a spherical mirror related to its radius of curvature?

     Jawaban

     $f=R/2$.

     This paraxial approximation applies to rays near the principal axis.

131. Kartu 131

     Pertanyaan

     How is a molecular formula obtained from an empirical formula?

     Jawaban

     $k=M_{\mathrm{molecular}}/M_{\mathrm{empirical}}$, then multiply every empirical subscript by the integer $k$.

132. Kartu 132

     Pertanyaan

     What is the capacitance of an ideal parallel-plate capacitor?

     Jawaban

     $C=\kappa\varepsilon_0A/d$.

     Larger plate area or dielectric constant raises capacitance; greater separation lowers it.

133. Kartu 133

     Pertanyaan

     What does Graham's law predict for two gas effusion rates?

     Jawaban

     $r_1/r_2=\sqrt{M_2/M_1}$.

     At the same temperature, effusion rate is inversely proportional to the square root of molar mass.

134. Kartu 134

     Pertanyaan

     Which relationship gives laminar flow through a cylindrical tube?

     Jawaban

     $Q=\dfrac{\pi r^4\Delta P}{8\eta L}$.

     Poiseuille flow is extremely sensitive to radius and assumes a Newtonian fluid in a long rigid tube.

135. Kartu 135

     Pertanyaan

     How do equilibrium constants combine when reactions are added?

     Jawaban

     Multiply them: $K_{\mathrm{overall}}=K_1K_2\cdots$.

     Reverse or scale each component reaction before applying the reciprocal or power rule.

136. Kartu 136

     Pertanyaan

     Which relationship defines average power?

     Jawaban

     $P=W/\Delta t$.

     Power is the rate of energy transfer and is measured in watts, where $1\ \mathrm{W}=1\ \mathrm{J/s}$.

137. Kartu 137

     Pertanyaan

     What voltage does an ideal concentration cell produce at $25^\circ\mathrm{C}$?

     Jawaban

     $E=(0.0592\ \mathrm{V}/n)\log(C_{\mathrm{high}}/C_{\mathrm{low}})$ for the simple same-ion setup. The voltage vanishes when concentrations equalize.

138. Kartu 138

     Pertanyaan

     Which equivalent forms give energy stored in a capacitor?

     Jawaban

     $U=\tfrac12CV^2=\tfrac12QV=Q^2/(2C)$.

     Use the form matching the known variables.

139. Kartu 139

     Pertanyaan

     How is standard free-energy change related to the equilibrium constant?

     Jawaban

     $\Delta G^\circ=-RT\ln K$.

     A large $K$ corresponds to negative $\Delta G^\circ$.

140. Kartu 140

     Pertanyaan

     What instantaneous power is delivered by a force to a moving object?

     Jawaban

     $P=\vec F\cdot\vec v=Fv\cos\theta$.

     Only the force component parallel to velocity transfers energy at that instant.

141. Kartu 141

     Pertanyaan

     How is percent yield calculated?

     Jawaban

     $\%\mathrm{yield}=100\times(\mathrm{actual\ yield})/(\mathrm{theoretical\ yield})$.

142. Kartu 142

     Pertanyaan

     What condition gives constructive interference in a double-slit experiment?

     Jawaban

     $d\sin\theta=m\lambda$ for integers $m$.

     For small angles on a screen, fringe position is approximately $y_m=m\lambda L/d$.

143. Kartu 143

     Pertanyaan

     What stoichiometric condition marks acid–base equivalence?

     Jawaban

     Acid equivalents equal base equivalents: $n_a|z_a|=n_b|z_b|$. For molarity and volume, $M_aV_a|z_a|=M_bV_b|z_b|$.

144. Kartu 144

     Pertanyaan

     What value is useful for the speed of light in vacuum?

     Jawaban

     Use $c\approx3.00\times10^8\ \mathrm{m/s}$. In a material, light travels at $v=c/n$.

145. Kartu 145

     Pertanyaan

     Which Doppler relationship applies to collinear motion in a stationary medium?

     Jawaban

     $f'=f\dfrac{v\pm v_o}{v\mp v_s}$.

     Choose signs that raise $f'$ when source and observer approach and lower it when they separate.

146. Kartu 146

     Pertanyaan

     What is the integrated rate law for a second-order reaction in one reactant?

     Jawaban

     $1/[A]_t=1/[A]_0+kt$.

     A plot of $1/[A]$ versus time is linear with slope $k$.

147. Kartu 147

     Pertanyaan

     What dimensionless quantity helps predict laminar versus turbulent pipe flow?

     Jawaban

     $Re=\rho vD/\eta$.

     Lower Reynolds number favors laminar flow; higher values make turbulence more likely.

148. Kartu 148

     Pertanyaan

     How is reaction free energy related to standard free energy and reaction quotient?

     Jawaban

     $\Delta G=\Delta G^\circ+RT\ln Q$.

     This predicts the favorable direction under nonstandard conditions.

149. Kartu 149

     Pertanyaan

     What is linear momentum?

     Jawaban

     $\vec p=m\vec v$.

     Momentum is a vector with SI units of $\mathrm{kg\,m/s}$.

150. Kartu 150

     Pertanyaan

     How do you identify the limiting reactant from available moles?

     Jawaban

     Compare $n_i/\nu_i$ for each reactant, where $\nu_i$ is its stoichiometric coefficient. The smallest ratio runs out first and sets the reaction extent.

151. Kartu 151

     Pertanyaan

     How do capacitors combine in parallel?

     Jawaban

     $C_{\mathrm{eq}}=\sum_iC_i$.

     Parallel capacitors share voltage and their stored charges add.

152. Kartu 152

     Pertanyaan

     How do you estimate the pH of a dilute strong monoprotic acid of concentration $C$?

     Jawaban

     Assuming complete dissociation and negligible water autoionization, $[H^+]\approx C$ and $\mathrm{pH}\approx-\log C$.

153. Kartu 153

     Pertanyaan

     What relationship connects impulse and momentum change?

     Jawaban

     $\vec J=\int\vec F\,dt=\Delta\vec p$. For a constant force, $\vec J=\vec F\Delta t$.

154. Kartu 154

     Pertanyaan

     What is the solubility-product expression for $M_aX_b(s)\rightleftharpoons aM+bX$?

     Jawaban

     $K_{sp}=[M]^a[X]^b$.

     The solid is omitted; dissolved-ion concentrations carry their stoichiometric exponents.

155. Kartu 155

     Pertanyaan

     What condition gives minima from a single slit of width $a$?

     Jawaban

     $a\sin\theta=m\lambda$ for $m=1,2,3,\ldots$.

     The central maximum lies between the first minima.

156. Kartu 156

     Pertanyaan

     Which way do electrons flow in both galvanic and electrolytic cells?

     Jawaban

     Electrons flow through the external circuit from anode to cathode. Oxidation is always at the anode; reduction is always at the cathode.

157. Kartu 157

     Pertanyaan

     How do capacitors combine in series?

     Jawaban

     $1/C_{\mathrm{eq}}=\sum_i1/C_i$.

     Series capacitors carry equal charge magnitude, and the equivalent capacitance is below the smallest one.

158. Kartu 158

     Pertanyaan

     Which equation adds molecular size and attraction corrections to the ideal gas law?

     Jawaban

     $\left(P+a\dfrac{n^2}{V^2}\right)(V-nb)=nRT$.

     The $a$ term corrects attractions; $b$ corrects finite molecular volume.

159. Kartu 159

     Pertanyaan

     What beat frequency is heard from two nearby tones?

     Jawaban

     $f_{\mathrm{beat}}=|f_1-f_2|$.

     Beats arise from alternating constructive and destructive interference.

160. Kartu 160

     Pertanyaan

     What near-Earth gravitational acceleration is useful for MCAT estimates?

     Jawaban

     Use $g\approx9.8\ \mathrm{m/s^2}$, or $10\ \mathrm{m/s^2}$ for quick order-of-magnitude work when the choices allow it.

161. Kartu 161

     Pertanyaan

     What weak-acid approximation estimates $[H^+]$ for initial concentration $C$?

     Jawaban

     $[H^+]\approx\sqrt{K_aC}$ when dissociation is small compared with $C$. Check that the resulting ionization is roughly below 5%.

162. Kartu 162

     Pertanyaan

     Why does a constriction in a horizontal ideal-fluid tube usually have lower static pressure?

     Jawaban

     Continuity raises the speed in the narrow section, and Bernoulli's relationship then requires lower static pressure when height is unchanged. This is the Venturi effect.

163. Kartu 163

     Pertanyaan

     How does a solid's length change for a small temperature shift?

     Jawaban

     $\Delta L=\alpha L_0\Delta T$.

     $\alpha$ is the linear expansion coefficient; the approximation assumes it stays nearly constant.

164. Kartu 164

     Pertanyaan

     When is total linear momentum conserved?

     Jawaban

     $\sum\vec p_i=\sum\vec p_f$ when the net external impulse on the chosen system is zero. Internal forces can redistribute momentum without changing the total.

165. Kartu 165

     Pertanyaan

     What relationship connects absorbance and concentration in a dilute solution?

     Jawaban

     $A=\varepsilon bc$.

     Beer–Lambert law uses molar absorptivity $\varepsilon$, path length $b$, and concentration $c$; it is most reliable in the linear dilute range.

166. Kartu 166

     Pertanyaan

     What magnetic force acts on a moving charge?

     Jawaban

     $F=|q|vB\sin\theta$.

     The force is perpendicular to both velocity and magnetic field, so it changes direction but does no work.

167. Kartu 167

     Pertanyaan

     How does the Arrhenius equation relate rate constant and temperature?

     Jawaban

     $k=Ae^{-E_a/(RT)}$. Equivalently, $\ln k=\ln A-E_a/(RT)$. Higher temperature or lower activation energy increases $k$.

168. Kartu 168

     Pertanyaan

     What is centripetal acceleration for uniform circular motion?

     Jawaban

     $a_c=v^2/r=\omega^2r$.

     It points toward the center even when speed is constant.

169. Kartu 169

     Pertanyaan

     How do ions in a salt bridge move to maintain electroneutrality in a galvanic cell?

     Jawaban

     Anions migrate toward the anode compartment, where oxidation creates excess positive charge. Cations migrate toward the cathode compartment, where reduction creates relative excess negative charge by consuming cations or producing anions. These migrations maintain charge neutrality.

170. Kartu 170

     Pertanyaan

     What is the maximum kinetic energy in the photoelectric effect?

     Jawaban

     $K_{\max}=hf-\phi$.

     Electrons are emitted when $hf\geq\phi$. Exactly at threshold, $hf=\phi$ and $K_{\max}=0$; positive kinetic energy requires $hf>\phi$.

171. Kartu 171

     Pertanyaan

     What molar volume is a useful ideal-gas reference at $0^\circ\mathrm{C}$ and $1\ \mathrm{atm}$?

     Jawaban

     About $22.4\ \mathrm{L/mol}$.

     This shortcut is tied to those stated conditions, not every convention labeled STP.

172. Kartu 172

     Pertanyaan

     What is the period of an ideal mass–spring oscillator?

     Jawaban

     $T=2\pi\sqrt{m/k}$.

     The small-amplitude period depends on mass and spring stiffness, not amplitude.

173. Kartu 173

     Pertanyaan

     For $MX_2(s)\rightleftharpoons M^{2+}+2X^-$, how is $K_{sp}$ related to molar solubility $s$ in pure water?

     Jawaban

     $K_{sp}=s(2s)^2=4s^3$.

     This relation changes when a common ion is already present.

174. Kartu 174

     Pertanyaan

     What does a dimensional-consistency check require of an equation?

     Jawaban

     Every term that is added or equated must have the same dimensions. A mismatch, such as adding energy to force, proves the equation or unit conversion is wrong.

175. Kartu 175

     Pertanyaan

     How is percent ionization of a weak acid calculated?

     Jawaban

     $\%\mathrm{ionization}=100\times[H^+]_{\mathrm{eq}}/[HA]_0$ for a monoprotic acid. Dilution generally raises percent ionization even while lowering $[H^+]$.

176. Kartu 176

     Pertanyaan

     What pressure difference does surface tension create across one spherical liquid–gas interface?

     Jawaban

     $\Delta P=2\gamma/r$.

     For a soap bubble with two interfaces, $\Delta P=4\gamma/r$. Smaller radii require larger pressure differences.

177. Kartu 177

     Pertanyaan

     What energy balance applies in an insulated calorimetry problem?

     Jawaban

     $\sum q=0$, so heat lost by hotter parts equals heat gained by colder parts and the calorimeter. Include every component named in the setup.

178. Kartu 178

     Pertanyaan

     What radius does a charged particle follow when moving perpendicular to a uniform magnetic field?

     Jawaban

     $r=mv/(|q|B)$.

     The magnetic force supplies centripetal force; faster or heavier particles curve less.

179. Kartu 179

     Pertanyaan

     How do you find concentration after mixing solutions of the same nonreacting solute?

     Jawaban

     $M_f=(M_1V_1+M_2V_2)/(V_1+V_2)$ when volumes are additive. If the solutes react, do stoichiometry before calculating the remaining concentration.

180. Kartu 180

     Pertanyaan

     What net inward force is required for circular motion?

     Jawaban

     $F_c=mv^2/r=m\omega^2r$.

     “Centripetal force” is the inward net force supplied by real forces, not an extra force.

180 kartu

MCAT Physics & Chemistry Equation Flashcards: Formulas, Units & When to Use Them

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