Question

How do the following changes affect the value of the equilibrium constant for a gas-phase exothermic reaction:

1. removal of a reactant
A. increase equilibrium constant
B. decrease equilibrium constant
C. no effect
2. removal of a product
A. increase equilibrium constant
B. decrease equilibrium constant
C. no effect
3. decrease in the volume
A. increase equilibrium constant
B. decrease equilibrium constant
C. no effect
4. decrease in the temperature
A. increase equilibrium constant
B. decrease equilibrium constant
C. no effect
5. addition of catalyst
A. increase equilibrium constant
B. decrease equilibrium constant
C. no effect

Answer 1

Removing a reactant decreases the equilibrium constant, removing a product increases it, decreasing the volume increases it, decreasing the temperature decreases it, and adding a catalyst has no effect on the equilibrium constant.

Step-by-step explanation:

1. Removal of a reactant: B. decrease equilibrium constant.

2. Removal of a product: A. increase equilibrium constant.

3. Decrease in volume: A. increase equilibrium constant.

4. Decrease in temperature: B. decrease equilibrium constant.

5. Addition of catalyst: C. no effect on equilibrium constant.

Answer 2

The removal of a reactant or product does not affect the equilibrium constant for a gas-phase exothermic reaction. A decrease in the volume may increase the equilibrium constant if there is a stoichiometric change in moles of gas, while a decrease in temperature results in a decrease of the equilibrium constant. The addition of a catalyst has no effect on the equilibrium constant.

Step-by-step explanation:

In response to how various changes affect the value of the equilibrium constant (K) for a gas-phase exothermic reaction:

1. Removal of a reactant: C. no effect on the equilibrium constant. The removal of a reactant will cause the position of equilibrium to shift to the left (according to Le Chatelier's principle), but it does not change the value of K.
2. Removal of a product: C. no effect on the equilibrium constant. While the removal of a product shifts the position of equilibrium to the right, the value of K remains unchanged.
3. Decrease in the volume: A. increase equilibrium constant only if the total moles of gas decrease as a result of shifting the equilibrium. This relies on the stoichiometry of the reaction and whether there is a difference in moles of gas between reactants and products.
4. Decrease in temperature: B. decrease equilibrium constant because a decrease in temperature favors the exothermic reaction, according to Le Chatelier’s principle, thus decreasing K.
5. Addition of catalyst: C. no effect on the equilibrium constant. Catalysts increase the rate at which equilibrium is achieved, but they do not change the position of the equilibrium or the value of K.