MCAT General Chemistry Freestanding Practice Questions: Equilibrium

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1. Which of the following manipulations is capable of changing the Keq of the reaction shown below?

N2 (g) + H2(g) 2 NH3(g)

  • A. Doubling the concentrations of N2 (g), H2(g), and NH3(g)
  • B. Tripling the volume of the reaction container
  • C. Increasing the pressure from 1 to 2 atm
  • D. Decreasing the temperature to from 298 K to 273 K

2. A group of scientists is studying the dynamics of the acetic acid dissociation below and bring the process to equilibrium under standard conditions. If the scientists then add 35 g of sodium acetate to the reaction container, which of the following will be true?

CH3COOH(aq) CH3COO-(aq) + H+ (aq)

  • A. Q > Keq and the reaction will move in reverse.
  • B. Q < Keq and the reaction will move forward.
  • C. Q > Keq and the reaction will move forward.
  • D. Q < Keq and the reaction will move in reverse.

3. Given the following equilibrium:

N2(g) + 3 H2(g) 2 NH3(g) ∆H = -91.8kJ

How would an increase in temperature affect the concentration of N2 at equilibrium?

  • A. The concentration of N2 will increase because of an increase in Keq.
  • B. The concentration of N2 will decrease because of an increase in Keq.
  • C. The concentration of N2 will increase because of a decrease in Keq.
  • D. The concentration of N2 will remain unchanged.

4. Na2SO4 is soluble in water. If NaCl(s) is added to a solution of Na2SO4(aq) so that the concentration of Na+ doubles, then the:

  • A. solubility constant of Na2SO4 increases while that of NaCl decreases.
  • B. solubility constants of Na2SO4 and NaCl both decrease.
  • C. solubility of Na2SO4 and NaCl both decrease.
  • D. solubility of Na2SO4 decreases while that of NaCl increases.

5. The equilibrium expression below corresponds to which of the following reactions?

  • A. 2 SO2(aq) + O2(g) 2 SO3(aq)
  • B. 2 SO3(aq) 2 SO2(aq) + O2(g)
  • C. 2 SO2(g) + O2(g) 2 SO3(g)
  • D. 2 SO3(g) 2 SO2(g) + O2(g)

6. Which of the following salts is least soluble in water?

  • A. PbI2 (Ksp = 7.9 × 10-9)
  • B. Mg(OH)2 (Ksp = 6.3 × 10-10)
  • C. Zn(IO3)2 (Ksp = 3.9 × 10-6)
  • D. SrF2 (Ksp = 2.6 × 10-9)

7. The water solubility of MgSO4 is approximately 25 g/100 mL at 20°C. Compared to a 0.25 g/mL solution of MgSO4 prepared at 20°C, a 0.25 g/mL solution prepared at 37°C will:

  • A. dissolve faster and have the same concentration of ions in solution.
  • B. dissolve faster and have a higher concentration of ions in solution.
  • C. dissolve slower and have a lower concentration of ions in solution.
  • D. dissolve slower and have the same concentration of ions in solution.

8. If the Ksp of KI is 1.45 × 10- 6 in propanol at 25°C, what would the Ksp of KI be in propane at the same temperature?

  • A. 1.84
  • B. 2.90 × 10-3
  • C. 1.81 × 10-6
  • D. 7.56 × 10-23

9. The Ksp of NaCl in water is 35.9 at 25°C. If 500 mL of 12 M NaOH(aq) and 500 mL of 12 M HCl(aq) solution both at 25°C are combined, what would best describe the resulting solution?

  • A. A small amount of NaCl(s) would precipitate.
  • B. There will be a 6 M aqueous solution of NaCl.
  • C. Enthalpy and entropy would increase.
  • D. The resulting solution would be slightly basic.