Name:______Date:______Period:_____

Equilibrium Practice

  1. How will the equilibrium shift if The following reaction is at equilibrium:

4NH3 (g) + 3O2 (g)↔ 6H2O (g) + 2N2 (g)

  1. The volume is increased
  2. Four moles of Helium gas is added
  3. A lit match is placed inside the container
  1. Chemical equilibrium is achieved when______

a) all of the reactants are used up.

b) the amounts of reactants and products are equal.

c) the rates of the forward and reverse reactions are equal.

d) both the forward and reverse reactions stop.

  1. A change in one of the conditions, such as concentration of a reactant, temperature, or pressure, affecting an equilibrium reaction is called a(n)______

a)catalyst

b)stimulus

c)shift

d)stress

  1. Which of the following is true regarding the equilibrium constant if more CO is added to the following equilibrium system?

2 CO (g) + O2 (g) ↔ 2CO2 (g)

a)the equilibrium constant is unchanged but the temperature increases.

b)the equilibrium constant must increase.

c)the equilibrium constant must decrease.

d)the equilibrium constant stays the same.

  1. Methanol Production:

a) What would happen to the equilibrium if the concentration of hydrogen (H2) was increased at constant temperature?

b) What would happen to the equilibrium if the concentration of carbon monoxide (CO) was decreased at constant temperature?

c) What would happen to the equilibrium if the temperature was increased?

6.Write an equilibrium constant expression for the following reactions at equilibrium:

a) 2 SO2 (g) + O2 (g) ↔ 2 SO3 (g)

b) 2 H2(g) + O2(g)↔ 2 H2O(g)

c) NH3(aq) + H2O(l)↔NH4+(aq) + OH-(aq)

  1. Indicate the equilibrium expression for the following reaction:

a) [X]2[Y][W]3[V]

b)

c)

d)

  1. a) Write the equilibrium law for the following reaction:

The reaction N2O4 (g)↔ 2 NO2(g) is endothermic with a ΔHo =+56.9 kJ/mol.

b) How will the amount of NO2 at equilibrium be affected by

  • adding N2O4
  • lowering the pressure
  • increasing the volume of the container
  • raising the temperature
  • addition He to the system
  • adding more NO2 to the system without changing pressure or temperature
  • adding a catalyst to the system

c) Which of these will alter the value of Keq

  1. For the rusting of iron initially at equilibrium, predict the shift in the reaction with each perturbation.

3 Fe(s) + 4 H2O (g) ↔Fe3O4 (s) + 4 H2 (g) + heat

a) Increase the amount of water

b) Decrease the volume by half

c) Remove Fe3O4 as it is formed

d) Add hydrogen gas to the mixture

e) Increase the temperature

Consider the chemical systemK = 4.6  109 L/mol.How do the equilibrium concentrationsof the reactants compare to the equilibrium concentration of the product?

a) They are much smaller

b) They are much bigger

c) They are about the same.

d) They have to be exactly equal

e) You can't tell from the information given.

  1. If the pressure on the equilibrium system N2(g) + 3H2(g) 2NH3(g) is increased,

a) the quantity of N2(g) increases.

b) the quantity of NH3(g) decreases.

c) the quantity of NH3(g) increases.

d) the quantities in the system do not change.

In Haber's process for the preparation of ammonia, the following equilibrium reaction is used:

3 H2 (g) + N2 (g) ↔ 2 NH3 (g)

  1. The equilibrium constant for this system is

  1. [NH3]

[N2][H2]

  1. [N2][H2]

[NH3]

  1. [N2][H2]3

[NH3]2

  1. [NH3]2

[N2][H2]3

  1. When producing ammonia using Haber's process, the temperature is kept quite high (about 550°C) in order to
  1. force the equilibrium position to the right.
  2. force the equilibrium position to the left.
  3. decrease the rate of loss of NH3.
  4. decrease the time required to reach equilibrium
  1. Tooth decay is the result of dissolving of tooth enamel, Ca5(PO4)3OH (s). In the mouth the following equilibrium is established.

Ca5(PO4)3OH (s) ↔5 Ca2+ (aq) + 3 PO43- (aq) + OH- (aq)

When sugar ferments, acid or H+ is formed on the teeth. Which of the following effect does this have on the equilibrium?

  1. It causes a reduction of OH- (aq) and tooth enamel Ca5(PO4)3OH (s) , to dissolve.
  2. It causes an increase in OH- (aq) and tooth enamel Ca5(PO4)3OH (s) , to reform.
  3. It causes an increase in OH- (aq)and tooth enamel , Ca5(PO4)3OH (s) , to dissolve.
  4. None of the above is correct.
  1. Which of the statements below is true concerning this reaction? Keq = 1.0 x 102

SO2 (g) + NO2 (g)  NO(g) + SO3(g)

  1. the concentration of the reactants is greater than the products.
  2. the concentration of the products is greater than the reactants.
  3. the reverse direction is favored
  4. both A and C are correct answers

15 Pressure only has an effect on reactions taking place in a

A)gas.C)solid.

B)liquid.D)closed container.