Endothermic reactions
In endothermic reactions, energy is taken in from the surroundings and the temperature of the surroundings decreases.
Watch this video to see how a decrease in temperature can be measured when barium hydroxide and ammonium chloride react.
Endothermic reaction between barium hydroxide and ammonium chloride
The slideshow describes an endothermic reaction between sodium carbonate and ethanoic acid.
Image caption, 1. Sodium carbonate powder is tipped into a beaker of ethanoic acid which contains a thermometer showing room temperature
Image caption, 2. The beaker now contains sodium ethanoate, water and carbon dioxide, and the thermometer is showing a fall in temperature, so this was an endothermic reaction
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Examples of endothermic reactions include:
- thermal decompositionType of reaction in which a compound breaks down to form two or more substances when it is heated. reactions
- the reaction of citric acid and sodium hydrogencarbonate
Everyday uses of endothermic reactions include instant ice packs which can be used to treat sports injuries.