JEE Advanced 2017 · Paper 2 · Chemistry Q9

← JEE Advanced 2017 · Paper 2

ChemistryMultiple correct+4 / -2Question 27 of 54

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

With increase in temperature, the value of

K

for exothermic reaction decreases because the entropy change of the system is positive

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 endothermic reaction increases because the entropy change of the system is negative

With increase in temperature, the value of

K

for exothermic reaction decreases because favourable change in entropy of the surroundings decreases

Answer and worked solution

Official answer: B, D

Surroundings. For the surroundings, $\Delta S_{surr}=-\dfrac{\Delta H}T$ .

Exothermic reactions. $\Delta S_{surr}>0$ helps the reaction. As $T$ rises this favourable term shrinks, so $K$ decreases. (D) is true.

Endothermic reactions. $\Delta S_{surr}<0$ hinders the reaction. As $T$ rises this unfavourable term shrinks, so $K$ increases. (B) is true.

(A) and (C) attribute the effect to the sign of the system's entropy change, which is not the reason. False.

(B), (D)

Topics:Equilibrium and Gibbs energy Entropy

← Previous question Next question →

JEE Advanced 2017 · Paper 2, Chemistry question 9