The Effect of Temperature on Keq – Practice

Questions:

1) For the following reactions, explain the impact of lower temperatures on Keq:

a) PCl5(g) + heat ⇌ PCl3(g) + Cl2(g) (endothermic)

b) 2SO2(g) + O2(g) ⇌ 2SO3(g) (-∆H)

2) For the following reactions, explain the impact of higher temperatures on Keq:

a) 2NOCl(g) ⇌ 2NO(g) + Cl2(g) (∆H)

b) H2(g) + I2(g) ⇌ 2HI(g) (exothermic)

3) The decomposition of dinitrogen tetroxide into nitrogen dioxide has a Keq value of 4.7 × 10–3 at 298K and 0.48 at 373K. Justify whether this reaction is endothermic or exothermic in the forward direction:

Quick Answers:

1a) Keq will decrease as a lower temperature will shift the equilibrium to the left.

b) Keq will increase as a lower temperature will shift the equilibrium to the right.

2a) Keq will increase as a higher temperature will shift the equilibrium to the right.

b) Keq will decrease as a higher temperature will shift the equilibrium to the left.

3) Keq increases at higher temperatures indicating a shift right. The equilibrium will shift in the endothermic direction at increased temperatures. Therefore, the reaction is endothermic in the forward direction.

Worked Answers: (coming soon)