Question

Consider the following reaction:

$N_2\left(g\right)+3H_2\left(g\right)\leftrightharpoons 2N{H}_3\left(g\right)$

What will happen if the temperature of the reacting system is decreased?

• A. An exothermic reaction will be favored.
• B. An endothermic reaction will be favored.
• C. A forward reaction will be favored.
• D. A backward reaction will be favored.

Answer 1

Answer: (B), (C)

The correct options are
B

An endothermic reaction will be favored.

C

A forward reaction will be favored.

When the temperature of the reaction is decreased, then, according to Le Chatelier's principle the equilibrium system will try to readjust itself to counteract this effect.

• If the temperature of the reacting system is decreased then the system will try to increase it. Therefore, an exothermic reaction will occur favoring a backward reaction. As a result, ammonia will decompose to form nitrogen and hydrogen.
• If the temperature of the reacting system is increased then the system will try to decrease it. Therefore, an endothermic reaction will occur favouring a forward reaction. As a result, ammonia will be formed from nitrogen and hydrogen.