8/19/2019 Worksheet 15 (Ch 12, 13, 14)

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Worksheet 15 (Ch 12, 13, 14)

1.  After placing ammonium carbonate in a container it is found that the total pressure of all the gases for thefollowing reaction at equilibrium is 1.45 atm.

(NH4)2CO3(s) 2 NH3(g ) + H2O(g) + CO2(g)

What is K  p for the reaction?

a. 0.0691 b. 17.7 c. 0.363 d. 0.0173 e. 2.10

2. 

The best choice of the following for a buffer that will be effective at pH of 1.8 and 25 degrees C, would be anacid component with a Ka equal to

a. 3.0 x 10-8  b. 1.9 x 10-9  c. 5.6 x 10-6  d. 6.6 x 10-4  e. 5.9 x 10-2 

3.  For the reaction, SnO2(s) + 2 CO(g) Sn(s) + 2 CO2(g), Kp is 0.025 at 500 oC. With the system atequilibrium, if the amount of SnO2(s) is doubled, then the partial pressure of CO2(g) will

a. double b. change unpredictably c. quadruple d. remain the same e. decrease

4. 

At a certain temperature, the percent dissociation (ionization) of chlorous acid, HClO2, in 1.63 M solution water

is 10.0%. Calculate the value of Ka for chlorous acid at this temperature.

a. 6.5 x 10-3  b. 1.6 x 10-1  c. 1.8 x 10-2  d. 1.0 x 10-1  e. 2.7 x 10-2 

5. 

For which reaction will K  p be smaller than K c at 25 oC?

a. N2(g) + 3 H2(g) 2 NH3(g) 

 b. CO2(g) + C(s) 2 CO(g) 

c. O3(g) + NO(g) NO2(g) + O2(g) 

d. H2(g) + F2(g) 2 HF(g) 

e. N2O4(g) 2 NO2(g) 

6. 

What is the pH of a solution prepared by dissolving 0.075 mol of Ba(OH)2 in water to give 545 mL of solution?

a. 0.56 b. 13.44 c. 12.84 d. 0.86 e. 13.14

7.  At a given temperature, K  p = 25 for the reaction, N2O4(g) 2 NO2(g).

For which equation is the value of Kp equal to 5?

a. NO2(g) 1/2 N2O4(g) 

 b. 4 NO2(g) 2 N2O4(g) 

c. 1/2 N2O4(g) NO2(g) 

d. 2 NO2(g) N2O4(g) 

e. 2 N2O4(g) 4 NO2(g)

8.  If the activation energy for the reverse reaction is less than the activation energy for the forward

reaction, the reaction is

a. faster in the forward direction b. a equilibrium c. endothermic

d. exothermic e. faster in reverse direction

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9.  Consider the reaction A(g) 2 B(g) for which Kp = 0.15. In which of the following case(s) will the reaction

 proceed to the right?

 p(A) p(B)

X 1.0 atm 1.0 atm

Y 0.010 atm 1.0 atm

Z 1.0 atm 0.010 atm

10.  K w is known to increase with increasing temperature. A solution whose pH = 7 at 60 oC would therefore be

a. acidic b. has [H3O+] = [OH-] c. neutral d. has [OH-] = 1 x 10-7  e. basic

11.  Consider the reaction, CO(g) + 3H2(g) CH4(g) + H2O(g) for which ∆Ho = -206 kJ.

Which of the following changes would drive the reaction at

equilibrium to the left?

12.  Ozone reacts with nitrogen dioxide according to the equation, 2 NO2(g) + O3(g) => N2O5(g) + O2(g). The rate

law is found to be rate = k[NO2]2[O3]. Which of the following mechanisms is consistent with the rate law?

a. NO2(g) + O3(g) NO5(g) fast equilibrium   NO5(g) + NO5(g) => N2O5(g) + 5/2 O2(g) slo  

 b. 2 NO2(g) + O3(g) N2(g) + 7/2 O2(g) fast equilibrium   N2(g) + 5/2 O2(g) => N2O5(g) slow 

c. NO2(g) + NO2(g) => N2O2(g) + O2(g) slow 

 N2O2(g) + O3(g) => N2O5(g) fast 

d. NO2(g) + NO2(g) N2O4(g) fast equilibrium   N2O4(g) + O3(g) => N2O5(g) + O2(g) slow 

e. NO2(g) + O3(g) => NO3(g) + O2(g) slow   NO2(g) + NO3(g) => N2O5(g) fast 

13.  A vessel that is at equilibrium contains 0.400 atm each of H2(g), I2(g) and HI(g). All of the HI is then removed

and the vessel is allowed to return to equilibrium. What is the new pressure of HI(g)? H2(g) + I2(g) 2 HI(g)

a. 0.533 b. 0.400 c. 0.800 d. 0.267 e. 0.133

14.  Calculate the pH of a 0.60 M solution of aniline(C6H5 NH2, K  b = 3.8 x 10-10.)

a. 9.18 b. 11.60 c. 4.82 d. 9.42 e. 2.40

15. 

Which of the following statements is false regarding the equilibrium constant K c?

a. K c is unitless 

 b. K c is independent on the initial concentrations. 

c. K c for a reaction at a particular temperature always has the same value.  

d. The numerical value of K c depends on the form of the balanced equation. 

e. K c for the reverse reaction is the negative of K c for the forward reaction. 

A. 

X and Y only

B. 

X only

C. 

X and Z only

D. 

Y only

E. 

Z only

I. Adding of H2(g)

II. Removing CO(g)

III. Reducing the volume of the container

IV. Adding a catalyst.

V. Increasing the volume of the container.

VI. Decreasing the temperature.VII. Increasing the temperature.

VIII. Adding CH4(g). 

a. 

II, IV, V, VII, VIII

b.  II, V, VII, VIII

c. 

I, II, III, VIId.  I, III, VIe.

 

E. I, III, IV, VI

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16.  Picric acid has been used in the leather industry and in etching copper. However, use in the laboratory has become restricted because it loses water on standing and can become shock sensitive and explode. At a

 particular temperature, it has an acid dissociation constant of 0.42. What is [H3O+] for a 0.20 M solution of

 picric acid?

a. 5.4 x 10-1 M 

 b. 8.4 x 10-2 M 

c. 1.5 x 10-1 M 

d. 7.1 x 10-3 M 

e. 2.9 x 10-1 M 

17.  Calculate K c for the gaseous reaction, 2 NO + O2  N2O4 given:

 NO(g) + 1/2 O2  NO2  K = 2.40 x 108 

 N2O4(g) 2 NO2(g) K = 2.50 x 10-4 

a. 9.60 x 1011 

 b. 6.00 x 104 

c. 3.84 x 1015 

d. 1.44 x 1013 

e. 2.30 x 1020 

18. 

Consider the following mechanism:

Cl2 => Cl+ + Cl- 

Cl- + H2S => HCl + HS- 

Cl+ + HS- => HCl + S

What is the role of chlorine? A. intermediate B. Catalyst C. reactant D. product

19. Consider the following equilibrium: PCl5(g) PCl3(g) + Cl2(g). 4.0 mol of PCl3(g) and 4.0 mol of Cl2(g) are

 placed into a 10.0 L flask at 300 oC and allowed to come to equilibrium. Analysis shows that 1.4 mol of Cl2(g) are present.

Determine the value of K c at this temperature.a. 13 b. 0.48 c. 0.75 d. 0.075 e. 4.8

20. 

What is the conjugate acid of HSbO42-?

a. H3O+ 

 b. H2Sb2- 

c. SbO43- 

d. SbO42- 

e. H2SbO4-