Which type of reaction releases heat?

The process that releases heat is characterized as an exothermic reaction. In this type of reaction, the energy stored in the chemical bonds of the reactants is released into the surroundings, often in the form of heat. This occurs when the energy required to break the bonds in the reactants is less than the energy released when new bonds are formed in the products. The result is a net release of energy, which warms the surrounding environment.

Exothermic reactions are commonly observed in various chemical processes such as combustion, where fuels react with oxygen to produce heat, or in respiration processes where glucose is converted into energy in living organisms. The fact that these reactions lead to an increase in temperature is a defining characteristic that distinguishes them from other reaction types.

In contrast, endothermic reactions absorb heat from their surroundings, leading to a decrease in temperature. Catalytic reactions involve catalysts that speed up the rate of a reaction but do not inherently determine whether heat is absorbed or released. Equilibrium reactions are a state where the rates of the forward and reverse reactions are equal, and they can involve both exothermic and endothermic processes at different stages.