Which type of reaction occurs when energy is absorbed before the reaction takes place?

In an endothermic reaction, energy is absorbed from the surroundings, which means that the reactants require an input of energy to proceed with the reaction. This absorption of energy typically occurs in the form of heat, resulting in a decrease in the temperature of the surroundings as the reaction takes place. This type of reaction is often characterized by the products having higher energy than the reactants, indicating that energy has been taken in during the process.

This distinguishes endothermic reactions from exothermic reactions, where energy is released, and the surroundings become warmer. Understanding the nature of endothermic reactions is crucial in various fields, such as chemistry and physics, as it influences how reactions are perceived and managed in practical applications.

Catalytic reactions, on the other hand, involve the use of a catalyst to speed up a reaction without being consumed, while combustion reactions refer specifically to reactions that involve the burning of a substance in oxygen, typically releasing energy. These distinctions clarify the specific role energy absorption plays in endothermic reactions compared to other types of reactions.