Chemistry C2: Exothermic and Endothermic Reactions

Exothermic reactions 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 

      - the reaction between water and calcium oxide          between acids & alkalis

Endothermic reactions take in energy from the surroundings

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:

- electrolysis                                                            - the thermal decomposition

- the reaction between ethanoic                         of calcium carbonate in

acid and sodium carbonate                                  a blast furnace