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Equilibrium Constants Practice Test

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A reversible chemical process is considered in equilibrium when the rate of the forward reaction equals the rate of the reverse reaction. The ratio of these reaction rates is called the equilibrium constant. Test your knowledge about equilibrium constants and their use with this ten question equilibrium constant practice test.

You may wish to review Chemical Equilibrium and Equilibrium Constants.

Answers appear at the end of the test.

Question 1

An equilibrium constant with a value K > 1 means:

a. there are more reactants than products at equilibrium
b. there are more products than reactants at equilibrium
c. there are the same amount of products and reactants at equilibrium
d. the reaction is not at equilibrium

Question 2

Equal amounts of reactants are poured into a suitable container. Given sufficient time, the reactants may be converted almost entirely to products if:

a. K is less than 1
b. K is greater than 1
c. K is equal to 1
d. K is equal to 0

Question 3

The equilibrium constant for the reaction

H2 (g) + I2 (g) ↔ 2 HI (g)

would be:

a. K = [HI]2/[H2][I2]
b. K = [H2][I2]/[HI]2
c. K = 2[HI]/[H2][I2]
d. K = [H2][I2]/2[HI]

Question 4

The equilibrium constant for the reaction

2 SO2 (g) + O2 (g) ↔ 2 SO3 (g)

would be:

a. K = 2[SO3]/2[SO2][O2]
b. K = 2[SO2][O2]/[SO3]
c. K = [SO3]2/[SO2]2[O2]
d. K = [SO2]2[O2]/[SO3]2

Question 5

The equilibrium constant for the reaction

Ca(HCO3)2 (s) ↔ CaO (s) + 2 CO2 (g) + H2O (g)

would be:

a. K = [CaO][CO2]2[H2O]/[Ca(HCO3)2]
b. K = [Ca(HCO3)2]/[CaO][CO2]2[H2O]
c. K = [CO2]2
d. K = [CO2]2[H2O]

Question 6

The equilibrium constant for the reaction

SnO2 (s) + 2 H2 (g) ↔ Sn (s) + 2 H2O (g)

would be:

a. K = [H2O]2/[H2]2
b. K = [Sn][H2O]2/[SnO][H2]2
c. K = [SnO][H2]2/[Sn][H2O]2
d. K = [H2]2/[H2O]2

Question 7

For the reaction

H2 (g) + Br2 (g) ↔ 2 HBr (g),

K = 4.0 x 10-2. For the reaction

2 HBr (g) ↔ H2 (g) + Br2 (g)

K =:

a. 4.0 x 10-2
b. 5
c. 25
d. 2.0 x 10-1

Question 8

At a certain temperature, K = 1 for the reaction

2 HCl (g) → H2 (g) + Cl2 (g)

At equilibrium, you can be certain that:

a. [H2] = [Cl2]
b. [HCl] = 2[H2]
c. [HCl] = [H2] = [Cl2] = 1
d. [H2][Cl2]/[HCl]2 = 1

Question 9

For the reaction: A + B ↔ C + D

6.0 moles of A and 5.0 moles of B are mixed together in a suitable container. When equilibrium is reached, 4.0 moles of C are produced.

The equilibrium constant for this reaction is:

a. K = 1/8
b. K = 8
c. K = 30/16
d. K = 16/30

Question 10

The Haber process is a method to produce ammonia from hydrogen and nitrogen gasses. The reaction is

N2 (g) + 3 H2 (g) ↔ 2 NH3 (g)

If hydrogen gas is added after the reaction has reached equilibrium, the reaction will:

a. shift to the right to produce more product
b. shift to the left to produce more reactants
c. stop. All the nitrogen gas has already been used up.
d. Need more information.

Answers

1. b. there are more products than reactants at equilibrium
2. b. K is greater than 1
3. a. K = [HI]2/[H2][I2]
4. c. K = [SO3]2/[SO2]2[O2]
5. d. K = [CO2]2[H2O]
6. a. K = [H2O]2/[H2]2
7. c. 25
8. d. [H2][Cl2]/[HCl]2 = 1
9. b. K = 8
10. a. shift to the right to produce more product

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