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Reactions and temperature changes

Exothermic and endothermic reactions

When a fuel burns, the surroundings become warmer. is transferred to the surroundings. This is an example of an reaction.

During some reactions, energy is transferred from the surroundings. This is called an reaction.

In endothermic reactions, energy enters. In exothermic reactions, energy exits.

Temperature change

For some reactions, it is possible to measure the temperature of the at the start and the temperature of the at the end.

The change in temperature indicates how exothermic or endothermic the reaction is.

ChangeReaction type
Increase in temperatureExothermic
Decrease in temperatureEndothermic
ChangeIncrease in temperature
Reaction typeExothermic
ChangeDecrease in temperature
Reaction typeEndothermic

The slideshow describes an exothermic reaction between dilute sodium hydroxide and hydrochloric acid, and an endothermic reaction between sodium carbonate and ethanoic acid.

Image gallerySkip image gallerySlide 1 of 4, Sodium hydroxide solution is poured into a beaker of hydrochloric acid which contains a thermometer showing room temperature., 1. Sodium hydroxide solution is poured into a beaker of hydrochloric acid which contains a thermometer showing room temperature

A study of the energy changes involved in chemical reactions, whether exothermic or endothermic