Exam 3 Review

Equillibrium

100

The following reaction is exothermic:

5CO₂(g) + I₂(g)  ->  I₂O₅(g) + 5CO(g) 

The yield of products could be increased by…

A.    decreasing the pressure.            

B.    decreasing the temperature. 

C.    decreasing the concentration of CO2.

D.    adding a catalyst.

B.    decreasing the temperature

200

Calculate the equilibrium constant, K_eq, for the following reaction at 25 C, if [NO]_eq = 0.106 M, [O₂]_eq = 0.122 M, and [NO₂]_eq = 0.129 M.

2NO(g) + O₂(g) -> 2NO₂(g)

A. 9.98

B. 12.1

C. 1.29

D. 94.1

E. 8.57

B. 12.1

300

Consider the following equilibria.  Which reaction will shift to the left when the volume is decreased?

A.    H₂(g) + Cl₂(g)  ->  2HCl(g)    

B.    2SO₃(g)  ->  2SO₂(g) + O₂(g)

C.    N2(g) + 3H₂(g)  ->  2NH₃(g)

D.    4Fe(s) + 3O₂(g)  ->  2Fe₂O₃(s)

E.    2HI(g)  ->  H₂(g) + I₂(g)

B.    2SO₃(g)  ->  2SO₂(g) + O₂(g)

400

Find the equilibrium constant, K_eq, for the following equilibrium. The initial concentrations of AB and A₂D are 0.30 M before they are mixed and when equilibrium is reached, the equilibrium concentration of A₂D is 0.20 M.

2AB(g) + C₂D(s) -> A₂D(g) + 2CB (s)

A. 1.25

B. 0.40

C. 2.5

D. 0.80

D. 0.80

500

What is the pH of a mixture of 50.0 mL of 0.10 M NaOH with 25.0 mL of 0.30 M HCl?

A. 0.667

B. 1.48

C. 12.52

D. 13.33

B. 1.48

Memorize

100

Which of the following is not a spectator ion?

A. Cl

B. ClO₄

C. F

D. Na

E. Sr

C. F

200

Which of the following is the strongest acid?

A.    HBr    

B.    HCl    

C.    H₂S

D.    H₂O

A.    HBr

300

Choose the stronger acid from each set.

Set I: HClO₂ or HClO₃

Set II: HBrO₃ or HClO₃

      Set I               Set II

A.   HClO₂                  HBrO₃

B.   HClO₂                  HClO₃

C.   HClO₃                  HBrO₃

D.   HClO₃                  HClO₃

D.   HClO₃                  HClO₃

400

Which of the following solutions will be acidic?

I. 1.0 M NaCl

II. 1.0 M CH₃CO₂Na

III. 1.0 M NH₄Cl

A. only I

B. only II

C. only III

D. II and III

E. I and II

C. only III

500

Which of the following pairs contains two weak acids?

A. HNO₃ and HF

B. HF and C₆H₅COOH

C. H₂SO₄ and H₂S

D. HCl and CH₃COOH

E. H₃PO₄ and HBr

B. HF and C₆H₅COOH

pH

100

Adding a few mg of NaF to 0.25 M aqueous solution of HF will...

HF (aq) + H₂O (l) -> F^- (aq) + H₃O⁺ (aq)

A. Decrease the pH of the solution as the concentration of [H₃O⁺] will decrease.

B. Increase the pH of the solution as the concentration of [H₃O⁺] will increase.

C. Increase the pH of the solution as the concentration of [H₃O⁺] will decrease.

D. Decrease the pH of the solution as the concentration of [H₃O⁺] will increase.

E. Have no effect on the pH.

C. Increase the pH of the solution as the concentration of [H₃O⁺] will decrease.

200

Calculate the pH of a buffer made by mixing 75.0 mL of 0.250 M CH₃COOH with 55.0 mL of 0.450 M NaCH₃COO. The K_a for CH₃COOH is 1.8 x 10^-5

A. 5.00

B. 4.87

C. 4.74

D. 4.62

B. 4.87

300

Which of the following solutions will have a pH of 1.3?

A. 0.05 M HF

B. 0.05 M CH₃CO₂H

C. 0.05 M NaOH

D. 0.05 M HI

D. 0.05 M HI

400

What is the pH of a solution of 0.12 M of benzoic acid (given pK_a=4.20)?

A. 11.44

B. 5.12

C. 0.56

D. 1.64

E. 2.56

E. 2.56

500

What is pH when 0.005 moles of HCl is added to 0.100 L of a buffer solution that is 0.100 M in CH₃CO₂H and 0.100 M NaCH₃CO₂? The Ka for acetic acid is 1.8 × 10^-5.  

A. 4.74    

B. 5.22 

C. 4.44 

D. 4.56

E. 4.26  

E. 4.26

Acids and Bases

100

What is the conjugate base of HNO₂?

A. H₂NO₂

B. HNO^-

C. NO

D. NO₂^-

D. NO₂^-

200

Which of the following solutions, all 0.010 M, has the highest pH? The lowest pH?

Ba(OH)₂    NH₃     NaOH

     highest pH       lowest pH

A.    Ba(OH)₂            NaOH

B.       NH₃                    NaOH

C.     NaOH                NH₃

D.    Ba(OH)₂              NH₃

E.        NH₃              Ba(OH)₂

D.    Ba(OH)₂              NH₃

300

Which combination is a Bronsted-Lowry conjugate acid-base pair?

A. HClO₂/ClO^-

B. HCO₂H/HCO₂^-

C. HCN/CH₃CN

D. H₃PO₄/HPO₄^2-

B. HCO₂H/HCO₂^-

400

Which of the following are acids?

I. HBrO

II. NaCl

III. NH₄F

A. I only

B. II only

C. III only

D. I and III

E. I, II, and III

A. I only

500

What is the pH of a 0.20 M solution of ammonia? The K_b value for ammonia is 1.8 x 10_-5

A. 9.56

B. 9.26

C. 4.74

D. 11.28

E. 2.72

D. 11.28

Surprise

100

Consider the following solutions of the weak acid HCN. Which would have the smallest percent dissociation.

A. 0.75 M

B. 2 x 10^-4 M

C. 1.0 M

D. 0.5 M

C. 1.0 M

200

Which of each pair has the higher pH? Assume an identical concentration for each solution?

Pair I (acids):

pyruvic acid, HC₃H₃O₃        K_a=4.1 x 10^-3

boric acid, H₃BO₃               K_a=5.4 x 10^-10

Pair II (bases):

pyridine, C₅H₅N                 K_b=1.7 x 10^-9

codeine, C₁₈H₂₁NO₃           K_b=1.6 x 10^-4

A. pyruvic acid and pyridine

B. boric acid and pyridine

C. pyruvic acid and codeine

D. boric acid and codeine

D. boric acid and codeine

300

What is the pH of 5.1 x 10^-4 M Sr(OH)₂?

A. 11.01

B. 3.29

C. 3.59

D. 10.71

E. 2.99

A. 11.01

400

What is the percent dissociation of a benzoic acid solution with pH = 2.59? The acid dissociation constant for this monoprotic acid is 6.5 x 10^-5.

A. 0.50%

B. 1.5%

C. 2.5%

D. 3.5%

C. 2.5%

500

A 0.10 M solution of HCN has a pH of 5.15.  Based on the following information, which statement below is true?

acid                   conc.           % ionization

butanoic acid     0.10 M               1.2%

benzoic acid      0.10 M               2.6%

A.    HCN is a stronger acid than both butanoic and benzoic acids.

B.    HCN is a weaker acid than both butanoic and benzoic acids.

C.    HCN is stronger than butanoic acid but weaker than benzoic acid. 

D.    HCN is weaker than butanoic acid but stronger than benzoic acid.

B.    HCN is a weaker acid than both butanoic and benzoic acids.