Why does decreasing temperature favor exothermic reactions?

Decreasing temperature favours exothermic reactions because they release heat, making them more likely to occur at lower temperatures.

In more detail, reactions can be either exothermic or endothermic. Exothermic reactions release heat into their surroundings, while endothermic reactions absorb heat. The direction in which a reaction proceeds is influenced by the temperature of the surroundings.

According to Le Chatelier's principle, if a system at equilibrium is subjected to a change in temperature, pressure, or concentration of components, the system will adjust itself to counteract the effect of the change. In the case of temperature, if the temperature is decreased, the system will try to produce more heat to compensate. Therefore, an exothermic reaction, which releases heat, will be favoured.

This is because the heat produced in an exothermic reaction is considered a product of the reaction. When the temperature is decreased, the system sees this as a decrease in the amount of product (heat), and so it responds by shifting the equilibrium to the right to produce more heat, thus favouring the exothermic reaction.

In contrast, an endothermic reaction, which absorbs heat, would be favoured by an increase in temperature. This is because the heat absorbed in an endothermic reaction is considered a reactant. When the temperature is increased, the system sees this as an increase in the amount of reactant (heat), and so it responds by shifting the equilibrium to the left to consume more heat, thus favouring the endothermic reaction.

So, in summary, decreasing the temperature favours exothermic reactions because they release heat, and the system will try to compensate for the decrease in temperature by producing more heat.