Free Printable Olympiad Equilibrium

1.

What is the correct equilibrium expression for the given reaction?

a)

$K_{eq}=\frac{\left[Cu\left(NH_3\right)_4^{2+}\right]\left[OH^-\right]}{\left[NH_3\right]}$

b)

$K_{eq}=\frac{\left[Cu\left(NH_3\right)_4^{2+}\right]\left[2OH^-\right]}{\left[4NH_3\right]}$

c)

$K_{eq}=\frac{\left[Cu\left(NH_3\right)_4^{2+}\right]\left[OH^-\right]^2}{\left[NH_3\right]^4}$

d)

$K_{eq}=\frac{\left[Cu\left(NH_3\right)_4^{2+}\right]\left[2OH^-\right]^2}{\left[4NH_3\right]^4}$

2.

Consider the reaction:

$H_{2\left(g\right)}+I_{2\left(g\right)}\Longleftrightarrow\ 2HI_{\left(g\right)}\ \ \ K_{eq}=???$

Into a 1.00L vessel, 1.00 mol hydrogen gas and 1.oo mol Iodine gas are placed at a high temperature. when the reaction mixture stops changing, it is found that 79.0% of the hydrogen gas has reacted. What is the equilibrium constant for this reaction at this temperature?

a)

14.2

b)

17.9

c)

35.8

d)

56.6

3.

The endothermic reaction shown below is at equilibrium in a sealed flast, with significant amounts of both $Ca\left(OH\right)_{2\left(s\right)}\ and\ CaO_{\left(s\right)}$ present. Which action will increase the amount of calcium hydroxide at equilibrium?

$Ca\left(OH\right)_{2\left(s\right)}\Longleftrightarrow\ CaO_{\left(s\right)}+H_2O_{\left(g\right)}\ \ \ \ \Delta H\degree>0$

a)

Crushing the Calcium hydroxide into smaller pieces

b)

Decreasing the temperature of the flask

c)

Adding more $CaO_{\left(s\right)}$ to the flask

d)

Adding Nitrogen gas to the flask

4.

At equilibrium, a solution contains 0.5 mol each of $Cd_{\left(aq\right)}^{2+},\ SCN_{\left(aq\right)}^-,\ and\ Cd\left(SCN\right)_{4\left(aq\right)}^{2-}.$ What is the solution's volume?

$Cd_{\left(aq\right)}^{2+}+4SCN_{\left(aq\right)}^-\Longleftrightarrow\ Cd\left(SCN\right)_{4\left(aq\right)\ }^{2-}\ \ \ \ \ \ K_f=1.0\ x\ 10^3$

a)

2.0L

b)

2.2L

c)

2.8L

d)

8.0L

5.

The diagrams below represent the progress of a reaction of A->B, with molecules of A represented by solid circles and molecules of B represented by open circles. Which statement best describes the reaction at t=1000s?

a)

The reaction is at equilibrium because the concentrations of A and B are no longer changing.

b)

The reaction is not at equilibrium because not all of the A has been consumed.

c)

The reaction is not at equilibrium because the concentrations of A and B are not equal.

d)

The reaction is not at equilibrium because the positions of the molecules are still changing.

6.

For which of the following reactions would the yield of products at equilibrium NOT increase at a higher pressure?

a)

$N_{2\left(g\right)}+O_{2\left(g\right)}\Longleftrightarrow\ 2NO_{\left(g\right)}$

b)

$Ti_{\left(s\right)}+2Cl_{2\left(g\right)}\Longleftrightarrow\ TiCl_{4\left(g\right)}$

c)

$2C_2H_{4\left(g\right)}+2H_2O_{\left(g\right)}\Longleftrightarrow\ 2C_2H_{6\left(g\right)}+O_{2\left(g\right)}$

d)

$4HCl_{\left(g\right)}+O_{2\left(g\right)}\Longleftrightarrow\ 2H_2O_{\left(l\right)}+\ 2Cl_{2\left(g\right)}$

7.

At 400K, this reaction has $K_p=8.2\ x\ 10^{-4}$

$SO_{3\left(g\right)}\Longleftrightarrow SO_{2\left(g\right)}+\ \frac{1}{2}O_{2\left(g\right)}$

What is Kp at 400K for the following reaction?

$2SO_{3\left(g\right)}\Longleftrightarrow\ 2SO_{2\left(g\right)}+O_{2\left(g\right)}$

a)

$6.7\ x\ 10^{-7}$

b)

$8.2\ x\ 10^{-4}$

c)

$1.6\ x\ 10^{-3}$

d)

$2.9\ x\ 10^{-2}$

8.

Sulfur trioxide is formed from the reaction of sulfur dioxide and oxygen:

$SO_{2\left(g\right)}+\frac{1}{2}O_{2\left(g\right)}\Longleftrightarrow\ SO_{3\left(g\right)}$

At 1000K, an equilibrium mixture has partial pressures of 0.562 bar sulfur dioxide, 0.101 bar oxygen, and 0.332 bar sulfur trioxide. What is the equilibrium constant Kp for the reaction at this temperature?

a)

1.86

b)

3.46

c)

5.85

d)

16.8

9.

IBr(g) is in equilibrium at 150 degrees Celsius:

$2IBr_{\left(g\right)}\Longleftrightarrow\ I_{2\left(g\right)}+Br_{2\left(g\right)}\ \ \ \ \ K=8.50\ x\ 10^{-3}$

Initially, a closed vessel at 150 degrees Celsius has a partial pressure of IBr of 0.350atm and partial pressures of $I_2\ and\ Br_2$ each of 0.750 atm. What is the partial pressure of IBr once the system reaches equilibrium?

a)

1.01 atm

b)

1.09 atm

c)

1.56 atm

d)

1.82 atm

10.

The following endothermic reaction is at equilibrium in a sealed container.

$PCl_{3\left(g\right)}+Cl_{2\left(g\right)}\Longleftrightarrow\ PCl_{5\left(g\right)}$

Which of the following changes would result in an increase in the number of moles of $PCl_{5\left(g\right)}$ present at equilibrium?

I. Increasing the temperature

II. Increasing the volume

a)

I only

b)

II only

c)

Both I and II

d)

Neither I nor II

11.

Sulfuryl chloride is in equilibrium with sulfur dioxide and chlorine gas:

$SO_2Cl_{2\left(g\right)}\Longleftrightarrow\ SO_{2\left(g\right)}+Cl_{2\left(g\right)}$

A system with a volume of 1.00L is in equilibrium at a certain temperature with sulfuryl chloride having a partial pressure of 1.00 bar and sulfur dioxide and chlorine gas both with partial pressures of 0.10 bar. By how much will the number of moles of sulfuryl chloride at equilibrium change if the volume is reduced to 0.50L?

a)

Increase 1-10%

b)

Increase 11-50%

c)

Decrease 1-10%

d)

Decrease 11-50%

12.

What is the ratio Kc/Kp for the following reaction at 723 degrees Celsius?

$O_{2\left(g\right)}+UO_2Cl_{2\left(g\right)}\Longleftrightarrow\ U_3O_{8\left(g\right)}+3Cl_{2\left(g\right)}$

a)

0.0122

b)

1.00

c)

59.4

d)

82.8

13.

A 60.0g sample of Calcium carbonate is heated to 950K in a 1.00L evacuated container, where it reacts according to the following equation:

$CaCO_{3\left(s\right)}\Longleftrightarrow\ CaO_{\left(s\right)}+CO_{2\left(g\right)}$

After equilibrium is attained, the pressure of carbon dioxide is 30.0 mm Hg. When the experiment is repeated using 120.0g calcium carbonate, what is the equilibrium pressure P?

a)

$15.0\ mm\ Hg\le P<30.0\ mm\ Hg$

b)

P=30.0 mm Hg

c)

30.0mmHg<P<60.0mmHg

d)

P=60.0mmHg

14.

Which of the following will increase the concentration of chlorine ion in a saturated solution of AgCl in contact with excess solid silver chloride?

I. Addition of AgCl(s)

II. Addition of ammonia

a)

I only

b)

II only

c)

Both I and II

d)

Neither I nor II

Olympiad Equilibrium

Total questions: 14

Worksheet time: 28mins

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