Chapter 17, Problem 31A

Interpretation Introduction

Interpretation: The effect of increase of temperature of an endothermic reaction on the reaction equilibrium needs to be explained.

Concept introduction: According to Le Chatelier's principle if any stress is given to the equilibrium, it will shift in a direction to reduce the given stress. If change in concentration, pressure or temperature takes place at equilibrium, it will shift in the direction to undo the change or its effect.

Answer to Problem 31A

The reaction will move or shift in forward direction.

Explanation of Solution

Consider a hypothetical endothermic reaction: $A+2B\rightleftharpoons C+D\Delta H=+250\text{ kJ}\cdot {\text{mol}}^{-1}$

In this reaction, 250 kJ is absorbed (indicated by the positive sign) when 1 mole of A reacts completely with 2 moles of B. The reverse reaction ( conversion of C and D into A and B) would be exothermic, emitting the same amount of heat.

If the temperature is increased, then the direction of equilibrium will shift so as to reduce the temperature. Since, heat is absorbed in forward direction the reaction will move towards forward direction when temperature increases.

Conclusion

The reaction will move or shift in forward direction.