Question

For a reaction taking place in a container in equilibrium with its surroundings, the effect of temperature on its equilibrium constant K in terms of change in entropy is described by:

• A. With increase in temperature, the value of K for exothermic reaction decreases because entropy change of the system is positive
• B. With increase in temperature, the value of K for endothermic reaction increases because unfavourable change in entropy of the surroundings decreases
• C. With increase in temperature, the value of K for endothermic reaction increases because the entropy change of the system is negative
• D. With increase in temperature, the value of K for exothermic reaction decreases because favourable change in entropy of the surrounding decreases

Answer 1

Answer: (B), (D)

The correct options are
B With increase in temperature, the value of K for endothermic reaction increases because unfavourable change in entropy of the surroundings decreases
D With increase in temperature, the value of K for exothermic reaction decreases because favourable change in entropy of the surrounding decreases

$\Delta S_{surr}=\frac{-\Delta H}{T_{surr}}$
For endothermic reaction, if $T_{surr}$ increases $\Delta S_{surr}$ will increase.
For exothermic reaction, if $T_{surr}$ increases $\Delta S_{surr}$ will decrease.
So, with increase in temperature, the value of K for endothermic reaction increases because unfavourable change in entropy of the surroundings decreases.
With increase in temperature, the value of K for exothermic reaction decreases because favourable change in entropy of the surrounding decreases.