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Endothermic Reaction Examples

List of Chemical Reactions that Absorb Heat


Photosynthesis is an endothermic reaction.

Photosynthesis is an endothermic reaction.

Frank Krahmer, Getty Images

An endothermic reaction is any chemical reaction that absorbs heat from its environment. Here's a list of examples of endothermic reactions. You can use these when asked to cite an example or to get ideas to set up a demonstration of an endothermic reaction or process.

Endothermic Chemical Reactions

  • reaction of barium hydroxide octahydrate crystals with dry ammonium chloride
  • dissolving ammonium chloride in water
  • reaction of thionyl chloride (SOCl2) with cobalt(II) sulfate heptahydrate
  • mixing water and ammonium nitrate
  • mixing water with potassium chloride
  • reacting ethanoic acid with sodium carbonate
  • photosynthesis (chlorophyll is used to react carbon dioxide plus water plus energy to make glucose and oxygen)

Endothermic Processes

These examples could be written as chemical reactions, but are more generally considered to be endothermic or heat-absorbing processes:

  • melting ice cubes
  • melting solid salts
  • evaporating liquid water
  • converting frost to water vapor (melting, boiling, and evaporation in general are endothermic processes)
  • making an anhydrous salt from a hydrate
  • forming a cation from an atom in the gas phase
  • splitting a gas molecule
  • separating ion pairs
  • cooking an egg
  • baking bread

Cold Projects

Ice Cream and Freezing Point Depression
Icy Endothermic Reaction
Make a Cold Pack from Hot Ice

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