Question

Consider the following system at equilibrium where H° = 111 kJ, and Kc = 6.30, at 723 K:

2NH3(g)--> N2(g) + 3H2(g)

If the TEMPERATURE on the equilibrium system is suddenly decreased:

1- the value of Kc

A. Increases

B. Decreases

C. Remains the same

2- The value of Qc

A. Is greater than Kc

B. Is equal to Kc

C. Is less than Kc

3- The reaction must:

A. Run in the forward direction to reestablish equilibrium.

B. Run in the reverse direction to restablish equilibrium.

C. Remain the same. Already at equilibrium.

4- The concentration of H2 will:

A. Increase.

B. Decrease.

C. Remain the same.

Consider the following system at equilibrium where H° = 198 kJ, and Kc = 2.90×10-2, at 1.15×103 K.

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

If the VOLUME of the equilibrium system is suddenly DECREASED at constant temperature:

1- The value of Kc

A. increases.

B. decreases.

C. remains the same.

2- The value of Qc

A. is greater than Kc.

B. is equal to Kc.

C. is less than Kc.

3- The reaction must:

A. run in the forward direction to reestablish equilibrium.

B. run in the reverse direction to reestablish equilibrium.

C. remain the same. It is already at equilibrium.

4- The number of moles of O2 will:

A. increase.

B. decrease.

C. remain the same.

Answer 1

Consider the following reaction at equilibrium: зн, (з) 2NH, (g) N, (g) For this reaction, AH -111 kJ and K 6.30 at 723 K = As the value of AH is positive, the reaction is endothermic For endothermic reactions, K will increase with increase in temperature and decreases with decrease in temperature. equilibrium is suddenly 1. So, if the temperature of the system which is at decreased, then K will decreas e. 2. Then the value of Q. is greater than K. 3. The reaction must run in the reverse direction to reestablish the equilibrium direction, the concentration of products will decrease 4. As the reaction run in reverse Thus, the concentration of H, will decrease.

Consider the following reaction at equilibrium: 2So, (g) 2SO, (g) 0, (g) For this reaction, AH =198 kJ and K 2.90 x10 at 1.15x103 K = As the value of AH is positive, the reaction is endothermic If the volume of the system is suddenly decreased, then the concentration of the species increases. 1. The value of K does not depend on the initial concentrations of the reactants, it depends only temperature on Here, the temperature is constant. Hence, the value of K remains the same 2. If the volume of the system is decreased, the concentrations will increase Then the value of Q. is greater than K 3. The reaction must run in the reverse direction to reestablish the equilibrium. 4. As the reaction run in reverse direction, the concentration of products will decrease Thus, the concentration of O, will decrease