When a chemical reaction occurs, energy is transferred to, or from, the decreasefromheathottersurroundingstemperaturethermometertotransferredwarmer, and there is often a temperature change.

When a fire burns it transfers decreasefromheathottersurroundingstemperaturethermometertotransferredwarmer energy to the surroundings. Objects near the fire become decreasefromheathottersurroundingstemperaturethermometertotransferredwarmer. The temperature rise can be measured with a decreasefromheathottersurroundingstemperaturethermometertotransferredwarmer.

Exothermic reactions transfer energy decreasefromheathottersurroundingstemperaturethermometertotransferredwarmer the surroundings. The energy is usually transferred as heat energy, causing the reaction mixture and its surroundings to become decreasefromheathottersurroundingstemperaturethermometertotransferredwarmer.
The decreasefromheathottersurroundingstemperaturethermometertotransferredwarmer increase can be detected using a thermometer.

Endothermic reactions take in energy decreasefromheathottersurroundingstemperaturethermometertotransferredwarmer the surroundings. The energy is usually decreasefromheathottersurroundingstemperaturethermometertotransferredwarmer as heat energy, causing the reaction mixture and its surroundings to get colder.
The temperature decreasefromheathottersurroundingstemperaturethermometertotransferredwarmer can also be detected using a thermometer.