Solutions for Chapter 06, Chemical Principles 7th edition

8/19/2019 Solutions for Chapter 06, Chemical Principles 7th edition

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Chapter 6

Chemical Equilibrium

Chemical Principles 7th Edition

Steven S. Zumdahl



15. Consider the following reactions at some temperature:

2NOCl(g)↔ 2NO(g) + Cl2(g) K = 1.6 × 10-5

2NO(g)↔ N2(g) + O2(g) K = 1 × 1031

For each reaction some quantities of the reactants were placed in separate

containers and allowed to come to equilibrium. Describe the relative amounts

of reactants and products that are present at equilibrium. At equilibrium, which

is faster, the forward or reverse reaction in each case?



17. Explain the difference between K , K p, and Q.



23. At a particular temperature a 2.00-L flask at equilibrium contains 2.80 ×

10-4 mol N2, 2.50 × 10-5 mol O2, and 2.00 × 10-2 mol N2O. Calculate K at thistemperature for the reaction

2N2(g) + O2(g)↔ 2N2O(g)

If [N2] = 2.00 × 10-4 M, [N2O] = 0.200 M, and [O2] = 0.00245 M, does this

represent a system at equilibrium?



29. In a study of the reaction

3Fe(s) + 4H2O(g)↔ Fe3O4(s) + 4H2(g)at 1200 K, it was observed that when the equilibrium partial pressure of water

vapor is 15.0 torr, the total pressure at equilibrium is 36.3 torr. Calculate K p for

this reaction at 1200 K.



37. The equilibrium constant is 0.0900 at 25ºC for the reaction

H2O(g) + Cl2O(g)↔ 2HOCl(g)For which of the following sets of conditions is the system at equilibrium? For

those which are not at equilibrium, in which direction will the system shift?

a. A 1.0-L flask contains 1.0 mole of HOCl, 0.10 mole of Cl2O, and 0.10 mole

of H2

O.

b. A 2.0-L flask contains 0.084 mole of HOCl, 0.080 mole of Cl2O, and 0.98

mole of H2O.

c. A 3.0-L flask contains 0.25 mole of HOCl, 0.0010 mole of Cl2O, and 0.56

mole of H2O.





47. At a particular temperature, K = 2.0 × 10-6 for the reaction

2CO2(g)↔ 2CO(g) + O2(g)If 2.0 moles of CO2 is initially placed into a 5.0-L vessel, calculate the

equilibrium concentrations of all species.



51. In which direction will the position of the equilibrium

2HI(g)↔ H2(g) + I2(g) be shifted for each of the following changes?

a. H2(g) is added.

b. I2(g) is removed.

c. HI(g) is removed.d. In a rigid reaction container, some Ar(g) is added.

e. The volume of the container is doubled.

f. The temperature is decreased (the reaction is exothermic).



61. Suppose the reaction system

UO2(s) + 4HF(g)↔ UF4(g) + 2H2O(g)has already reached equilibrium. Predict the effect that each of the following

changes will have on the equilibrium position. Tell whether the equilibrium

will shift to the right, will shift to the left, or will not be affected.

a. More UO2

(s) is added to the system.

b. The reaction is performed in a glass vessel; HF(g) attacks and reacts with

glass.

c. Water vapor is removed.



63. Consider the decomposition of the compound C5H6O3 as follows:

C5H6O3(g) → C2H6(g) + 3CO(g)When a 5.63-g sample of pure C5H6O3(g) was sealed in an otherwise empty

2.50-L flask and heated to 200°C, the pressure in the flask gradually rose to

1.63 atm and remained at that value. Calculate K for this reaction. .



71. A 2.4156-g sample of PCl5 was placed in a empty 2.000-L flask and

allowed to decompose to PCl3 and Cl2 at 250.0°C:PCl5(g)↔ PCl3(g) + Cl2(g)

At equilibrium the total pressure inside the flask was observed to be 358.7 torr.

a. Calculate the partial pressure of each gas at equilibrium and the value of K p

at 250.0°C.

b. What are the new equilibrium pressures if 0.250 mol of Cl2 gas is added to

the flak?





Solutions for Chapter 06, Chemical Principles 7th edition

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