EQUILIBRIUM REVIEW SHEET



EQUILIBRIUM REVIEW SHEET

1. Why does an increase in the temperature cause a reaction to speed up?

The increase in temperature increases the velocity of the molecules resulting in an increased chance of a collision with sufficient energy occurring.

2. Why don’t all collisions between reactant molecules produce products?

They may not have sufficient energy or the molecules may not be in the correct orientation.

3. Is the statement “At equilibrium, the concentration of reactants equals the

concentration of products.” True or false ?

FALSE: The concentration does not need to be equal. At equilibrium, the rates of the forward and reverse reaction are equal.

4. What is the equilibrium constant expression for the reaction between HCl and

O2 ? 4 HCl (g) + O2 (g) ( 2 H2O (g) + 2 Cl2 (g)

K = [Cl2]2 [H2O]2

[O2] [HCl]4

5. What is the equilibrium constant expression for the decomposition of

Mg(OH)2 ? Mg(OH)2 (s) ( MgO (s) + H2O (g)

K = [MgO] [H2O] Note: [ ] of solids is assumed to be 1, so

[Mg(OH)2] you can cross them out of the equation

6. If the concentration of N2 gas is decreased, which way will the reaction shift ?

N2H4 (g) + O2 (g) ( N2 (g) + 2 H2O (g)

Pulls the reaction to the right to replace the nitrogen.

7. Will an increase in pressure cause the reaction below to shift to the right or

the left ? N2 (g) + 3 Br2 (l) ( 2 NBr3 (s)

Moves toward the side with fewer moles to decrease the pressure.

8. What is the equilibrium constant for the reaction between carbon monoxide,

CO, and hydrogen gas, H2, if at equilibrium, the concentration of CO is

0.304 M, H2 is 0.313 M, CH4 is 0.0956 M, and H2O is 0.0956 M ?

CO (g) + 3 H2 (g) ( CH4 (g) + H2O (g)

K = [CH4] [H2O] = (0.0956) (0.0956) = 0.980

[CO] [H2]3 (0.304) (0.313)3

9. What is the Ksp expression for the dissolution of solid Sn(ClO3)2 in water ?

10. What is the Ksp of BaCrO4 (s) if the solubility is 1.1 x 10-5 M ?

11. Why does an increase in the concentration of reactant cause a reaction to speed up?

Higher concentration means more collisions

12. Refer to the diagram

i. Which letter represents the energy of the products of a reaction? A

ii. Which letter represents the energy of the reaction? B

iii. Which letter represents the activation energy of a reaction? D

iv. Which letter represents the catalyzed reaction pathway? C

13. Write the equilibrium expression and calculate the equilibrium constant, K,

for the reaction below, at each set of equilibrium concentrations.

C2H4O2 (aq) ( C2H3O2- (aq) + H+ (aq)

K = [H+] [C2H3O2-]

[C2H4O2]

Experiment Equilibrium concentrations

[C2H4O2] [H+] [C2H3O2-]

I 1.0 M 0.0042 M 0.0042 M K = 1.8 x 10-5

II 0.50 M 0.0030 M 0.0030 M K = 1.8 x 10-5

III 2.0 M 0.0060 M 0.0060 M K = 1.8 x 10-5

16. What would happen to the position of the equilibrium when the following

changes are made to the equilibrium reaction below ?

2 SO2 (g) + O2 (g) ( 2 SO3 (g)

a. SO2 is removed from the reaction vessel.

b. SO3 is added to the reaction vessel.

c. Oxygen is removed from the reaction vessel.

17. Predict the effect of increasing the temperature on the position of each

equilibrium below.

a. H2 (g) + Cl2 (g) ( 2 HCl (g) + heat

b. 2 NH3 (g) + heat ( N2 (g) + 3 H2 (g)

c. CO2 (g) + H2 (g) + heat ( CO(g) + H2O (g)

18. The solubility of PbSO4 (s) is 1.3 x 10-4 M at 25 (C. What is the Ksp ?

19. Copper (II) sulfide has a Ksp of 8.0 x 10-45. What is the solubility of CuS in

water ?

20. If the equilibrium constant for the reaction below is 51.47, the concentration

of HI is 0.50 M, and the concentration of H2 is 0.069 M, what is the

concentration of I2? H2 (g) + I2 (g) ( 2 HI (g)

K = [HI]2 51.47 = (0.50)2 x = 0.70

[H2] [I2] (0.69) (x)

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