Energy Changes

Definition of Exothermic Reactions

Exothermic reactions are chemical reactions in which energy is released to the surroundings in the form of heat. This means that the temperature of the surroundings increases during the reaction.

Characteristics of Exothermic Reactions

• The temperature of the reaction mixture increases during the reaction.
• The temperature of the surroundings increases as energy is released to the environment.
• The products of the reaction have less energy than the reactants.
• The energy change is represented by a negative value (e.g., -50 kJ/mol).

Examples of Exothermic Reactions

• Combustion reactions, such as the burning of wood or gas.
• Neutralization reactions between acids and bases.
• Respiration in living organisms.
• The reaction between sodium and chlorine to form sodium chloride.