What type of reaction absorbs heat energy?

An endothermic reaction is characterized by the absorption of heat energy from the surroundings. In these reactions, the total energy of the products is greater than that of the reactants, indicating that energy has been absorbed to facilitate the conversion of reactants into products. This energy absorption often leads to a decrease in temperature of the surrounding environment, as heat is drawn in.

In contrast, exothermic reactions release heat energy, increasing the temperature of the surroundings. Catalytic reactions involve the presence of a catalyst that speeds up the reaction without being consumed, but they do not inherently classify the energy dynamics of the reaction itself. Redox reactions describe the transfer of electrons between species and can be either exothermic or endothermic, depending on the specific reaction context. Thus, endothermic specifically identifies reactions where heat is absorbed, fulfilling the criteria of the question.