Question

What is the effect of increasing the temperature of an endothermic reaction mixture at equilibrium? Of decreasing the temperature?

Answer 1

We use heat, `Delta`, as a virtual particle in the equilibrium to answer this question.

Explanation:

In an exothermic reaction, heat is evolved:

`ArightleftharpoonsB+Delta`

And in an endothermic reaction, heat is absorbed:

`A+DeltarightleftharpoonsB`

Of course, at a different temperature a new equilibrium might pertain, but the initial change, the initial response of the equilibrium
(which is after all only what Le Chatelier's principle predicts!) is to resist the temperature change (i.e. the external perturbation), by shifting the direction of the equilibrium appropriately to absorb or evolve heat.

And thus the equilibrium should move towards reactants if temperature is raised in an exothermic reaction; and towards products in an endothermic reaction. Remember my comments reagarding `"initial change"`.