Chapter 17, Problem 61A

Interpretation Introduction

Interpretation:

Whether the value of keq for a given equilibrium increases or decreases when temperature of the system is increased needs to be explained.

Concept introduction:

According to Le Chatelier’s principle, when concentration of the reactants and products are changed then equilibrium position also changes with the time. On lowering the temperature, the equilibrium also shifts towards the right side or product side and more products are formed but not always. For an endothermic reaction, lowering of temperature shifts equilibrium to the left side so there is a stress on equilibrium by increasing or decreasing of the concentration of reactants and products.

Answer to Problem 61A

On increasing the temperature, the equilibrium shift to left side or equilibrium is decreases.

Explanation of Solution

Given information:

${\text{PCl}}_{\text{5}}{\left(\text{g}\right)}_{}\underset{}{\rightleftharpoons }{\text{ PCl}}_{\text{3}}\left(\text{g}\right){\text{ + Cl}}_{\text{2}}{\left(\text{g}\right)}_{}\text{+ heat}$

When temperature increasesand heat is produced as a product, then the equilibrium of the reaction shifts to the left side or reactants side.

According to Le Chatelier’s principle, by changing the temperature, the equilibrium position also changes. As temperature decreases, the equilibrium shifts towards the right side or product side but not always. On the other hand, at constant temperature, the equilibrium is not affected.

So, there is a stress on equilibrium by increasing or decreasing of the concentration of reactants and products.

When some reactant is removed, then equilibrium is disturbed as rate of formation decreases. So the stress relieved by converting products to reactants and equilibrium shifts to left. In this way, according to Le Chatelier’s, principle, the equilibrium shifts to left by removing the reactants to attain the equilibrium quickly.

Conclusion

On increasing the temperature, the equilibrium shifts to left side or equilibrium decreases.