Name______Date______

Chapter 13 Review

Fill in the blanks:

Chemical equilibrium is the state where the concentrations of both reactants and products

is __1__ over time. At equilibrium the __2__ of the forward and reverse reactions are equal.

The law of __3__ states that for a chemical reaction j A + k B D l C + m D, the equilibrium

expression is given by __4__. K is called the __5__.

An equilibrium position never depends on the amount of a pure __6__ or __7__, so these

are omitted from the equilibrium expression. A small value of K means that the equilibrium lies

far to the __8__. When calculating equilibrium amounts, a(n) __9__ is used. This shows the

given __10__ concentrations or pressures and defines the __11__ needed to reach equilibrium.

The amounts can be expressed in __12__ or __13__.

For a gas phase reaction, either Kc or Kp can be used; the relationship between them is

defined by the equation __14__, where Δn represents __15__ minus __16__. __17__ allows us

to qualitatively predict the effects of changes in __18__, __19__ or __20__ on a system at

equilibrium.

1.______11. ______

2. ______12. ______

3. ______13. ______

4. ______14. ______

5. ______15. ______

6. ______16. ______

7. ______17. ______

8. ______18. ______

9. ______19 ______

10.______20. ______

1. The reaction H2(g) + I2(g) D 2 HI(g) has Kp = 45.9 at 763 K. A particular equilibrium

mixture at that temperature contains gaseous HI at a partial pressure of 4.00 atm and hydrogen

gas at a partial pressure of 0.200 atm. What is the partial pressure of I2?

2. Calculate Kp for H2O(g) + ½ O2(g) D H2O2(g) at 600 K, using the following data:

H2(g) + O2(g) D H2O2(g) Kp = 2.3 x 106 at 600 K

2 H2(g) + O2(g) D 2 H2O(g) Kp = 1.8 x 1037 at 600 K

3. Given the equation 2 NOCl(g) D 2 NO(g) + Cl2(g) the equilibrium constant Kc is 0.0150 at

115ºC. Calculate Kp.

4. For the equilibrium PCl5(g) + heat D PCl3(g) + Cl2(g) give the effect of each of the following:

a. increased temperature

b. increased pressure

c. higher concentration of Cl2

d. higher concentration of PCl5

5. In a 10.0 L evacuated chamber, 0.500 mol H2 and 0.500 mol I2 are reacted at 448ºC.

H2(g) + I2(g) D 2 HI(g)

At the given temperature, Kc = 50.0 for the reaction.

a. What is the value of Kp?

b. What is the total pressure in the chamber?

6. A 3:1 starting mixture of H2 and N2 comes to equilibrium at 450.ºC. The mixture at

equilibrium is 9.6% NH3, 22.6% N2, and 67.8% H2 at 60.0 atm.

a. What are the values of Kp and Kc for this reaction?

b. Determine the initial pressure of each component.

7. At a particular temperature, assume that Kc = 1.00 x 102 for the reaction

H2(g) + F2(g) D 2 HF(g)

a. In an experiment, 2.00 mol H2 and 2.00 mol F2 are introduced into a 1.00-L flask. Calculate

the concentrations of all species when equilibrium is reached.

b. To the equilibrium mixture in part a, an additional 0.50 mol H2 is added. Calculate the new

equilibrium concentrations of H2, F2, and HF.

8. The molar solubility of silver carbonate is 0.032 M. Calculate Ksp.

9. Calculate the molar solubility of Ag2SO4 (Ksp = 1.5 x 10–5) in the following solutions:

(a) pure water

(b) 0.15 M Al2(SO4)3

10. At 35°C, Kc = 1.6 x 10–5 for the reaction 2 NOCl(g) D 2 NO(g) + Cl2(g)

If 2.0 mol NO and 1.0 mol Cl2 are placed into a 1.0-L flask, calculate the equilibrium concentrations of all species. (Remember to think about what a small K value means, and THINK about whether your answers make sense!)

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