AP Chemistry PRACTICE TEST: Equilibrium, Acids, & Solubility (Ch. 15, 16 & 17)

Name: ______date: ______

Multiple Choice Section: (2 points each)

1.  You studied the reaction, Fe3+ + SCN- FeSCN2+ + Energy. Which of the following would shift the equilibrium to the reactants?

a.  Inrease [ Fe3+].

b.  Remove energy.

c.  increase [SCN-].

d.  Add energy

2.  An equilibrium constant much larger than one indicates:

a.  a reaction that makes lots of products.

b.  a reaction that does not make many products.

c.  a reaction that reaches equilibrium quickly.

d.  a reaction that takes a long time to reach equilibrium.

3.  In the following reaction at equilibrium, the concentration of each substance is [ A ] = 2 M; [B] = 2 M; [C] = 1 M; [D] = 2 M. What is the value of Keq, (the equilibrium constant)? 2 A + B 3 C + 2 D

a.  0.50

b.  0.75

c.  1.0

d.  1.3

e.  5.0

4.  Which of the theories of acids and bases would explain the following reaction:

HI + NH3 à NH4+1 + I-1

a.  Bronsted Lowry

b.  Bronsted Lowry and Lewis

c.  Arrhenius and Bronsted Lowry

d.  Arrhenius and Lewis

5.  The addition of CaCl2 to water would result in:

a.  An acidic solution

b.  A basic solution

c.  A neutral solution

d.  A buffer

6.  In a titration experiment based on the equation below, 45.0 mL of SnCl2 solution requires 20.0 mL of standard 0.10 M FeCl3 solution to reach the equivalence point. The concentration of Sn2- in the original solution is:

Sn2- + 2Fe3+ à Sn4- + 2Fe2-

a.  0.022

b.  0.089

c.  0.044

d.  0.11

e.  0.45

7.  What volume of 0.150M HCl is required to neutralize 25.0 mL of 0.120M Ba(OH)2?

a.  20.0 mL

b.  30.0 mL

c.  40.0 mL

d.  60.0 mL

e.  80.0 m

8.  Which of the following would result in the lowest pH?

a.  0.1 M Co(ClO4)2

b.  0.1 M RbCN

c.  0.1M Sr(NO3)2

d.  0.1M KC2H3O2

9.  2NOBr (g) 2NO (g) + Br2 (g)

The reaction above came to equilibrium at a temperature of 100oC. At equilibrium the partial pressure due to NOBr was 4 atm, the partial pressure due to NO was 4 atm, and the partial pressure due to Br2 was 2 atm. What is the equilibrium constant, Kp, for this reaction at 100oC?

a.  ¼

b.  ½

c.  1

d.  2

e.  4

10.  Of the following, ______is a weak acid. A) HBr B) HF C) HClO4 D) HCl E) HNO3

11.  At 1285oC the equilibrium constant for the reaction Br2 (g ) 2 Br (g) is Kc = 1.04 x 10-3. A 0.200 L vessel containing an equilibrium misture of the gases has 0.245 grams of Br2(g) in it. What is the mass of Br (g) in the vessel?

a.  0.0451 g

b.  0.00282 g

c.  0.00767 g

d.  0.0140 g

12.  The conjugate base of HSO4- is:

a)  H2SO4 b) SO4 2- c) H3SO4 + HSO4+

13.  The value of Ka for HSO4- is 1 x 10-2. What is the value for Kb for SO4-2?

a.  1 x 10-12

b.  1 x 10-8

c.  1 x 10-2

d.  1 x 102

e.  1 x 105

14.  If 0.630 grams of nitric acid are added to 1 Liter of water at 25oC, what is the pOH of the solution? (Assume that the addition of the acid does not change the overall volume of the solution significantly)

a.  0.01

b.  0.1

c.  12

d.  2

e.  3

15.  The titration below shows the titration of a weak base with a strong acid:

Which of the following values most accurately approximates the pKb of the weak base?

a.  5.2

b.  1.8

c.  9.8

d.  4.2

16.  A solution containing which one of the following pairs of substances will be a buffer solution?

A) NaI, HI

B) KBr, HBr

C) RbCl, HCl

D) CsF, HF

E) none of the above

17.  The solubility of lead (II) chloride (PbCl2) is 1.6 × 10-2 M. What is the Ksp of PbCl2?

A) 5.0 × 10-4

B) 4.1 × 10-6

C) 3.1 × 10-7

D) 1.6 × 10-5

E) 1.6 × 10-2

18.  Consider the following table of values.

Which compound listed below has the greatest molar solubility in water?

A)

B)

C) AgI

D)

E)

19.  Using the data in the table, which of the conjugate bases below is the strongest base?

Acid Ka

HOAc 1.8 x 10-5

HCHO2 1.8 x 10-4

HClO 3.0 x 10-8

HF 6.8 x 10-4

A) F- B) ClO- C) CHO2 – D) OAc- E) OAc- and CHO2-

Short Answer:

  1. At 200oC the equilibrium constant for the reaction

2NO (g) N2 (g) + O2 (g)

is Kc = 2.4 x 103. If the initial concentration of NO is 0.200 M, what are the equilibrium concentrations of NO, N2, and O2?

  1. A mixture of .550 mol of H2 and .320 mol of I2 is placed in a 4.500L container at 448oC and allowed to come to equilibrium. Analysis of the equilibrium mixture shows that the concentration of HI is .140 M. Calculate Kc at 448oC for the reaction: (3 points)

H2 (g) + I2 (g) ↔2HI (g)

  1. I prepared a 0.25 M solution of acetic acid and found its pH at 25oC. I found the pH to be 2.19. Calculate Ka for acetic acid and the percentage of acid that is ionized in this 0.25M solution. (4 points)
  1. Calculate the pH of a 0.25M solution of hydrofluoric acid. Ka = 6.8 x 10-4. (4 points)
  1. Predict the products of the following acid-base reactions, and predict whether the equilibrium lies to the left or the right of the equation.
  2. O-2 (aq) + H2O (l)
  1. CH3COOH (aq) + HS- (aq)
  1. Calculate the pH of a buffer composed of 0.29M lactic acid and 0.15M sodium lactate. The Ka of lactic acid is 1.4 x 10-4
  1. Calculate the pH in the solution formed by adding 10.0 mL of 0.050 M NaOH to 40.0 mL of 0.0250 M benzoic acid (C6H5COOH, Ka = 6.3 × 10-5) .
  1. Will Ag2SO4 precipitate when 100 mL of 0.05 M AgNO3 is mixed with 10 mL of 5.0 x 10-2 M Na2SO4 solution? (Ksp = 1.5 x 10-5)
  1. Suggest a way to separate the Mg2+ ion in a mixture with the K+ ion. Be sure to explain what will happen with the resulting products.