Question

Raising the temperature of an equilibrium system [MP PMT$1987$]
A.Favours the exothermic reaction only
B.Favours the endothermic reaction only
C.Favours both the exothermic and endothermic reactions
D.Favours neither the exothermic nor endothermic reactions

Answer 1

Hint: If temperature changes it will cause stress in the system. Whenever the temperature of the system increases any system will shift the equilibrium towards a direction in such a way that decreases the temperature so that it can neutralize the change and restore equilibrium.

Complete answer:When a chemical system is at equilibrium and reaction conditions are changed so that the reaction system is no longer at an equilibrium state. Then the system will try to achieve a new equilibrium that partially counteracts the change in conditions.

Now if the temperature of that chemical system changes, the reaction equilibrium constant is different at this new temperature. In this situation, Le-Chatelier’s principle can be used to determine which direction an equilibrium shifts so that it partially counteracts the change in conditions.

Here in the given question, the temperature of an equilibrium system is increased. According to Le-Chatelier’s principle, the system will try to compensate for the temperature increases and the equilibrium will shift toward the forward direction which means the system will favor endothermic reactions, the direction with positive $\Lambda {{H}^{O}}$. The endothermic reaction partially counteracts the increased temperature. In this case, the shift is to produce more products.
Therefore, raising the temperature of an equilibrium system favors the endothermic reaction only.

Thus, option (B) is correct.

Note: In the same way when the temperature of a chemical system decreases, the reaction equilibrium shifts to partially increase the temperature that is in the exothermic direction with negative $\Lambda {{H}^{O}}$. In this case, the shift is to produce more reactants.