AP BIOLOGY

Detailed explanation-1: -Chemical reactions that release energy are called exothermic. In exothermic reactions, more energy is released when the bonds are formed in the products than is used to break the bonds in the reactants. Exothermic reactions are accompanied by an increase in temperature of the reaction mixture.

Detailed explanation-2: -Energy is used to break bonds in reactants, and energy is released when new bonds form in products. Endothermic reactions absorb energy, and exothermic reactions release energy.

Detailed explanation-3: -Where is the exothermic heat energy coming from? The heat comes from the energy stored in the chemical bonds of the reactant molecules–which is greater than the energy stored in the chemical bonds of product molecules.