Question

The thermal dissociation of equilibrium of $CaCO_3 $ (s) is studied under different conditions $ CaCO_3 \, ( g) \rightleftharpoons CaCO ( g ) + CO_2 ( g)$
For this equilibrium, the correct statement(s) is/are

• A. $\Delta H$ is dependent on $T$
• B. $K$ is independent of the initial amount of $CaCO_3$
• C. $K$ is dependent on the pressure of $CO_2$ at a given $T$
• D. $\Delta H$ is independent of the catalyst, if any

Answer 1

Answer: (A), (B), (D)

(A) The expression for the enthalpy change is $\Delta H = C _{ p } \Delta T$ and for spontaneity of the reaction $\Delta G$ should be negative.
Hence, the enthalpy of the reaction is temperature-dependent.
(B) Equilibrium constant, $K$ is independent of the initial amount of calcium carbonate and is dependent only on temperature.
(C) Equilibrium constant depends on temperature but it is independent of pressure.
(D) Presence of catalyst lowers the activation energy but, the enthalpy of reaction is not affected.