Exothermic

Exothermic refers to a process or reaction that releases energy in the form of heat. It is the opposite of an endothermic process, which absorbs heat from the surroundings.

Overview

In an exothermic reaction, the energy needed to start the reaction is less than the energy that is subsequently released, so there is a net release of energy. This can be represented in a chemical equation as:

Reactants → Products + Energy

This energy is usually in the form of heat, but it can also be in the form of light, electricity, or sound.

Examples of Exothermic Reactions

Some common examples of exothermic reactions include:

• Combustion reactions, such as the burning of coal, wood, or natural gas
• Neutralization reactions, where an acid and a base react to form water and a salt
• The reaction between water and calcium oxide, which produces calcium hydroxide and releases a large amount of heat
• The process of respiration in living organisms, where glucose and oxygen are converted into carbon dioxide, water, and energy

Applications of Exothermic Reactions

Exothermic reactions have many practical applications. They are used in:

• Heat packs: These contain a supersaturated solution of a salt such as sodium acetate. When the solution is disturbed, it triggers an exothermic reaction that releases heat.
• Self-heating cans: These use an exothermic reaction between quicklime (calcium oxide) and water to heat up the contents of the can.
• Fireworks: The colors in fireworks are produced by exothermic reactions of different metal salts.
• Power plants: Many power plants, including coal and natural gas plants, rely on exothermic reactions to produce heat that is then converted into electricity.

See Also

• Endothermic
• Chemical reaction
• Energy
• Heat
• Thermodynamics

Exothermic Resources
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