Exothermic and Endothermic reactions

• When a chemical reaction happens, energy is transferred to or from the surroundings.

• When energy is transferred to the surroundings, this is called an exothermic reaction and usually feels hot.

• When energy is taken in from the surroundings, this is called an endothermic reaction and usually feels cold.

Reactions that release energy:

In a combustion reaction, fuel is burned and reacts with oxygen to release energy.

Respiration is the chemical change that takes place inside living cells. Glucose and oxygen are used to release energy that organisms need to live.

Reactions that absorb energy:

Photosynthesis absorbs energy from sunlight, allowing plants to make glucose and oxygen from carbon dioxide and water.