Question

The thermal decomposition equilibrium of $Ca{CO}_3\left(s\right)$ is studied under different conditions.
$Ca{CO}_3\left(s\right)\rightleftharpoons CaO\left(s\right)+{CO}_2\left(g\right)$
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 $Ca{CO}_3$
• C. $K$ is dependent on the pressure of ${CO}_2$ at a given temperature ($T$)
• D. $\Delta H$ is independent of catalyst if any

Answer 1

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

The correct options are
A $\Delta H$ is dependent on $T$
B $K$ is independent of the initial amount of $Ca{CO}_3$
D $\Delta H$ is independent of catalyst if any

(I) By kirchoff's equation,

$\frac{△H_2-△H_1}{T_2-T_1}=△C_P$

So, $△H$ is dependent on $T$.

(II) $K_{eq}$ for the reaction $Ca{CO}_3\left(s\right)\rightleftharpoons CaO\left(s\right)+{CO}_2\left(g\right)$$\Rightarrow K_{eq}=\frac{\left[CaO\right]\left[{CO}_2\right]}{\left[{CaCO}_3\right]}$

But, $CaO$ & ${CaCO}_3$ are pure solids, so their concentration is taken as unity.

$\Rightarrow K_{eq}=\left[{CO}_2\right]$; which is independent of $Ca{CO}_3$.

(III) $△H$ is independent of catalyst.