JEE PYQ: Thermodynamics Question 36
Question 36 - 2019 (11 Jan Shift 1)
For the chemical reaction $\text{X} \rightleftharpoons \text{Y}$, the standard reaction Gibbs energy depends on temperature T (in K) as
$\Delta_r G^\circ$ (in kJ mol$^{-1}$) $= 120 - \dfrac{3}{8}T$
The major component of the reaction mixture at T is:
(1) Y if T = 300 K
(2) Y if T = 280 K
(3) X if T = 350 K
(4) X if T = 315 K
Show Answer
Answer: (4)
Solution
At 315 K: $\Delta G^\circ = 120 - \dfrac{3}{8} \times 315 = 120 - 118.125 =$ positive. Since $\Delta G^\circ$ is positive then $K_{eq} < 1$. So $\dfrac{[\text{Y}]}{[\text{X}]} < 1$, therefore $[\text{X}] > [\text{Y}]$.
BETA
