5.1+Exothermic+and+endothermic+reactions

When a chemical reaction occurs, energy is transferred to, or from, the surroundings - and there is often a temperature change. For example, when a bonfire burns it transfers heat energy to the surroundings. Objects near a bonfire become warmer. The temperature rise can be measured with a thermometer.

Exothermic reactions
These are reactions that **transfer energy to the surroundings**. The energy is usually transferred as heat energy, causing the reaction mixture and its surroundings to become hotter. The temperature increase can be detected using a thermometer. Some examples of exothermic reactions are:
 * burning
 * neutralisation reactions between acids and alkalis
 * the reaction between water and calcium oxide

Endothermic reactions
These are reactions that **take in energy from the surroundings**. The energy is usually transferred as heat energy, causing the reaction mixture and its surroundings to get colder. The temperature decrease can also be detected using a thermometer. Some examples of endothermic reactions are: Here are 2 videos from clipbank: [] __**Exothermic reactions**__ []
 * Electrolysis
 * the reaction between ethanoic acid and sodium carbonate
 * the Thermal decomposition of calcium carbonate in a blast furnace
 * __Endothermic reactions__**