1. Exothermic reactions are reactions that release energy into the environment in the form of heat.
2. Exothermic reactions feel warm or hot or may even be explosive. A simple example of an exothermic reaction is combustion, such as lighting a candle. An initial input of energy causes oxygen and wax react to produce carbon dioxide, water, and heat.
3. An endothermic process is any process which requires or absorbs energy from its surroundings, usually in the form of heat.
4. It may be a chemical process, such as dissolving ammonium nitrate in water, or a physical process, such as the melting of ice cubes.