5 Steps to a 5 AP Chemistry

AP Chemistry Practice Exam 2  333

57.A solution of a weak base is titrated with a solu-
tion of a standard strong acid. The progress of the
titration is followed with a pH meter. Which of
the following observations would occur?

(A) At the equivalence point, the pH is below 7.

(B) The pH of the solution gradually decreases

throughout the experiment.

(C) At the equivalence point, the pH is 7.

(D) The pOH at the equivalence point equals the

pKbof the base.

(E) After the equivalence point, the pH becomes

constant because this is the buffer region.

58.When potassium carbonate is dissolved in water

(A) the solution is neutral.

(B) the solution is basic because of hydrolysis of

the CO 3 2–ion.

(C) the solution is basic because of hydrolysis of

the K+ion.

(D) the solution is acidic because of hydrolysis of

the K+ion.

(E) the solution is acidic because of hydrolysis of

the CO 3 2–ion.

59.Determine the OH–(aq) concentration in 0.10 M
pyridine (C 5 H 5 N) solution. (Kbfor pyridine is
9 × 10 –9.)

(A) 9 × 10 –9M

(B) 5 × 10 –6M

(C) 7 × 10 –3M

(D) 1 × 10 –1M

(E) 3 × 10 –5M

What is the equilibrium constant for the above

reaction? The successive acid dissociation constants

for H 2 S are 9.5 × 10 –8(Ka1) and 1 × 10 –19(Ka2).

Ksp, the solubility product constant, for FeS

equals 5.0 × 10 –18.

(A) 9.5 × 10 –27/5.0 × 10 –18

(B) 5.0 × 10 –18/ 9.5 × 10 –27

(C) 5.0 × 10 –18/9.5 × 10 –8

(D) 9.5 × 10 –8/5.0 × 10 –18

(E) 1 × 10 –19/5.0 × 10 –18

61.

exothermic

An equilibrium mixture of the reactants is placed

in a sealed container at 150°C. The amount of

the product may be increased by which of the

following changes?

I. adding 1 mol of Ar(g) to the container

II. decreasing the volume of the container

III. raising the temperature of the container

(A) I only

(B) II and III

(C) III only

(D) I and II

(E) II only

62.Kspfor Cr(OH) 3 is 1.6 × 10 –30. What is the molar

solubility of this compound in water?

Choose one of the following for questions 63–66.

(A) There is no change in the voltage.

(B) The voltage becomes zero.

(C) The voltage increases.

(D) The voltage decreases, but stays positive.

(E) The voltage becomes negative.

The following reaction takes place in a voltaic cell:

Zn(s) +Cu^2 +(1 M) →Cu(s) +Zn^2 +(1 M)

The cell has its voltage measured and found to be

+1.10 volts.

63.What happens to the voltage when deionized

water is added to the zinc compartment?

64.What happens to the cell voltage when the

copper electrode is made larger?

65.What happens to the cell voltage when the salt

bridge is replaced with a zinc wire?

66.What happens to the cell voltage after the cell has

operated for 15 min?

(E)^2 1.6 10× −^30

(D) 1.6 10× −^30 / 27

(C) 1.6 10× −^30

(B)^4 1.6 10× −^30 / 27

(A)^4 1 6 10. × −^30

C H (g) + H O(g) 22 2 CH CHO(g) 3

FeS(s)+2H (aq)+2Fe (aq)+H S(aq)+ 2

GO ON TO THE NEXT PAGE