Discussion Forum



1)

The thermal dissociation of equilibrium of CaCO3 (s)  is studied under different conditions.

 $CaCO_{3}(s)\rightleftharpoons CaO(s)+ CO_{2}(g)$

 For this equilibrium , the correct statement (s) is (are)


A) $ \triangle H$ is dependent on T

B) K is independent of the initial amount $CaCO_{3}$

C) K is dependent on the pressure of $CO_{2}$ at given T

D) $ \triangle H$ is independent of the catalyst , if any

Answer:

Option A,B,C,D

Explanation:

Plan   Heat of reaction is dependent on temperature (Kirchhoff's equation) in a heterogeneous system, the equilibrium constant is independent on the molar concentration of solid species.

 Heat of reaction is not affected by catalyst. It lower activation energy.

 $CaCO_{3} \rightleftharpoons CaO(s)+CO_{2}(g)$

 By Kirchhoff's equation

$\triangle H_2^0(at T_{2})=\triangle H_1^0(at T_{1})+\triangle C_{p}(T_{2}-T_{1})$

 $\triangle H^0$ varies with temperature.

Thus, (a) ... correct

 $k= p_{co_{2}}$

 k is dependent on the pressure of CO2 but independent of the molar concentration of CaCO3.

Thus, (b) and (c) are correct.

 At a given temperature, addition of  catalyst lowers activation energy, $\triangle H$  remaining constant

 Thus , (d) also correct.

 1252021248_c21.JPG

 Ea  = Activation energy in absence of a catalyst

Ea'= Activation energy in presence of catalyst