4.3 Energy of Reactions

Understand that chemical reactions can give off or absorb heat energy.

Study Guide

Explain each concept

è The law of conservation of energy states that energy is neither created nor destroyed.

è Energy released in exothermic reactions can be a product in a chemical equation.

è Energy absorbed in endothermic reactions can be a reactant in a chemical equation.

è Activation energy is the energy needed to start a chemical reaction.

è Energy diagrams indicate whether a reaction is exothermic or endothermic.

è The rate of a chemical reaction is affected by temperature, concentration, surface area, and the presence of a catalyst or inhibitor.

è Raising the temperature, increasing the concentration, increasing the surface area, and adding a catalyst can increase the rate of a reaction.