Revise: EquilibriaTemperature

Altering the temperature of an equilibrium mixture results in a shift depending on the enthalpy change of the reaction.

Consider the equilibrium between colourless dinitrogen tetroxide and brown nitrogen dioxide.

An increase in temperature favours the endothermic reaction.

In the above equilibrium, the enthalpy change shows that the forward reaction is endothermic. Increasing the temperature will shift the equilibrium to the right hand side.

This results in more nitrogen dioxide being formed and the reaction mixture becoming darker in colour.

A decrease in temperature favours the exothermic reaction.

In the equilibrium above, decreasing the temperature will favour the backwards reaction.

This will shift the equilibrium to the left, resulting in the formation of more dinitrogen tetroxide and the reaction mixture becoming lighter in colour.