PSI Barbering Practice Exam

Which term describes a chemical reaction that requires energy or heat absorption from an external source?

1. Exothermic

2. Endothermic

3. Combustion

4. Reversible

The correct answer is: Endothermic

The term that describes a chemical reaction which requires energy or heat absorption from an external source is "endothermic." In these reactions, the system absorbs heat from its surroundings, leading to a temperature decrease in the surrounding environment as energy is utilized to break bonds and initiate the reaction. In contrast, exothermic reactions release energy, usually in the form of heat, to the surroundings, resulting in an increase in the surrounding temperature. Combustion refers specifically to a type of exothermic reaction involving the reaction of a substance with oxygen to produce heat and light. Finally, reversible reactions can proceed in either direction and are not specifically characterized by their energy absorption or release, as they can involve both endothermic and exothermic processes. Thus, endothermic is the accurate term for reactions that absorb heat from external sources.