Chapter U6.122, Problem 5E

Interpretation Introduction

Interpretation: The effect of heating on following equilibrium mixture needs to be describe which endothermic in nature:

  $\text{2NiO(s) }\rightleftharpoons {\text{ 2Ni(s) + O}}_{\text{2}}\text{(g)}$

Concept introduction: According to LeChatlier's principle, when a dynamic equilibrium is subjected to a change in either concentration or temperature or pressure, then the position of equilibrium will shift in such a direction that it nullifies the change.

For example:

  $\text{A + B }\rightleftharpoons \text{ C}$ is a system at equilibrium.

If concentration of A is increased by adding some more amount of A at equilibrium, then left side concentration is increasing, so to nullify this change, equilibrium shifts towards right side.Hence, forward reaction or formation of C is favoured in this case.

Answer to Problem 5E

The concentration of reactants will decrease and that of products will increase and hence, resulting in increase in ${\text{K}}_{\text{eq}}$ value.

Explanation of Solution

The given equilibrium mixture described by endothermic equation is:

  $\text{2NiO(s) }\rightleftharpoons {\text{ 2Ni(s) + O}}_{\text{2}}\text{(g)}$

The endothermic equation represents that the thermal energy is absorbed via the reaction. So, the reaction can be rewritten as:

  $\text{2NiO(s) + heat }\rightleftharpoons {\text{ 2Ni(s) + O}}_{\text{2}}\text{(g)}$

From the above equation it can be interpreted that heat is acting as a reactant so, heating the equilibrium mixture means adding more amount of heat to the system. Now, according to LeChatlier's principle, the equilibrium will shift in forward direction (product side as the reactant is increasing) in order to nullify the change. Thus, on adding heat to the given endothermic equation, the concentration of reactants will decrease and that of products will increase and hence, resulting in increase in ${\text{K}}_{\text{eq}}$ value.