Princeton 2012/Barron 4th ed.
AP Practice Problems
Unit 12 – Equilibrium (Part II)
Multiple Choice (no calculator)
1. The solubility product, Ksp, of AgCl
is 1.8×10-10. Which of the following
expressions is equal to the solubility
of AgCl? (P9.9)
4. The solubility of strontium fluoride
in water is 1×10-3 M at room
temperature. What is the value of
the solubility product for SrF2?
(P9.23)
a. (1.8×10-10)2 molar
b.
molar
c. 1.8×10-10 molar
d. (2)(1.8×10-10) molar
e.
molar
2. Which of the following expressions
is equal to the Ksp of Ag2CO3?
(P9.20)
a.
b.
c.
d.
e.
Ksp = [Ag+][CO3-2]
Ksp = [Ag+][CO3-2]2
Ksp = [Ag+]2[CO3-2]
Ksp = [Ag+]2[CO3-2]2
Ksp = [Ag+]2[CO3-2]3
3. If the solubility of BF2 is equal to x,
which of the following expressions is
equal to the solubility product, Ksp,
for BF2? (P9.21)
a.
b.
c.
d.
e.
x2
2x2
x3
2x3
4x3
a.
b.
c.
d.
e.
2×10-3
4×10-6
2×10-6
4×10-9
2×10-9
5. The solubility product of PbS in
water is 3×10-14 molar. What is the
solubility product constant, Ksp, for
PbS? (P9.30)
a.
b.
c.
d.
e.
2×10-7
9×10-7
3×10-14
3×10-28
9×10-28
6. For a particular salt, the solution
process is endothermic. As the
temperature at which the salt is
dissolved increases, which of the
following will occur? (P10.5)
a. Ksp will increase, and the salt
will become more soluble.
b. Ksp will decrease, and the salt
will become more soluble.
c. Ksp will increase, and the salt
will become less soluble.
d. Ksp will decrease, and the salt
will become less soluble.
e. Ksp will not change, and the
salt will become more
soluble.
Princeton 2012/Barron 4th ed.
Essays
1. At 298 K, the value of the equilibrium constant, K, for the reaction below is 0.036. (P8.6)
H2O(l) ↔ H2O(g)
a. What is the sign of ∆S0 for the reaction listed above at 298K?
b. What is the sign of ∆H0 for the reaction listed above at 298K?
c. What is the sign of ∆G0 for the reaction listed above at 298K?
d. At approximately what temperature will ∆G for the reaction be equal to zero?
2. The value of the solubility product, Ksp, for calcium hydroxide, Ca(OH)2, is 5.5×10-6 at
25°C (P9.2a,d)
a. Write the Ksp expression for calcium hydroxide.
b. If 1.0 mole of OH- is added to 500 mL of a saturated Ca(OH)2 solution, what will
be the resulting Ca+2 concentration? Assume that the volume of the solution does
not change.
3. For sodium chloride, the solution process with water is endothermic. (P9.4a,c)
a. Describe the change in entropy when sodium chloride dissociates into aqueous
particles.
b. The solubility product of Ce2(SO4)3 decreases as temperature increases. Is the
solution process for this salt endothermic or exothermic? Justify your answer.
Princeton 2012/Barron 4th ed.
4. The value fo the solubility product, Ksp, for the reaction below is 1.0×10-6 at 25°C.
(P10.1a, b, d)
BaF2(s) ↔ Ba+2(aq) + 2F-(aq)
a. Write the Ksp expression for BaF2.
b. What is the concentration of F- ions in a saturated solution at 25°C?
c. What is the value of ∆G for the dissociation of BaF2 at 25°C?
5. The values for the solubility products for the two reactions below are given at 25°C.
(P10.4)
CaCO3(s) ↔ Ca+2(aq) + CO3-2(aq)
CaSO4(s) ↔ Ca+2(aq) + SO4-2(aq)
Ksp = 2.8×10-9
Ksp = 9.1×10-6
a. What is the concentration of CO3-2 ions in a saturated 1.00 liter solution of CaCO3
at 25°C?
b. Excess CaSO4(s) is placed in the solution in (a). Assume that the volume of the
solution does not change.
i. What is the concentration of the SO4-2 ion?
ii. What is the concentration of the CO3-2 ion?
c. A 0.20 mole sample of CaCl2 is placed in the solution in (b). Assume that the
volume of the solution does not change.
i. What is the concentration of the Ca+2 ion?
ii. What is the concentration of the SO4-2 ion?
iii. What is the concentration of the CO3-2 ion?
Princeton 2012/Barron 4th ed.
Answer Key – Equilibrium Part II
Multiple Choice
1. E
2. C
3. E
4. D
5. E
6. A
Essays
1. a. positive (product more random than reactant)
b. positive (liquid water to water vapor is endothermic)
c. positive (use ∆G0 = -RTlnK)
d. 373 (when ∆G = 0, liquid water and water vapor are in equilibrium meaning it is at the
boiling point of water which is 100°C)
2. a. Ksp = [Ca+2][OH-]2
b. 1.4×10-6 M (molarity of OH- is 2.0 M; use 5.5×10-6 = [Ca+2][2.0]2)
3. a. entropy increases when a salt dissociates because aqueous particles have more
randomness than a solid
b. exothermic - Ce2(SO4)3 becomes less soluble as temperature increases
4. a. Ksp = [Ba+2][F-]2
b. 0.006 M (use 1.0×10-6 = [x][2x]2)
c. 34,000 J which means the reaction is not spontaneous under standard conditions (use
∆G0 = -RTlnK)
5. a. 5.3×10-5 M (use Ksp = [Ca+2][CO3-2] so 2.8×10-9 = [x][x])
b.i. 3.0×10-3 M (use Ksp = [Ca+2][SO4-2] so 3.0×10-3 = [x][x])
b.ii. 9.3×10-7 M (use the value of Ca+2 from part b.i. so 2.8×10-9 = [3.0×10-3][CO3-2])
c.i. 0.20 M (0.20 mol/1.00 L)
c.ii. 4.6×10-5 M (use answer from c.i. for Ca+2 concentration in 3.0×10-3 = [0.20][SO4-2])
c.iii. 1.4×10-8 M (use answer from c.i. for Ca+2 concentration in 2.8×10-9 = [0.20][CO3-2])