Examples of Endothermic Reactions

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

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Cold Packs and Endothermic Reactions

By Anne Marie Helmenstine, Ph.D.

A good example of an endothermic reaction includes dissolving a salt. It doesn't have to be table salt, nor does the solvent need to be water.

• The reaction of barium hydroxide octahydrate crystals with dry ammonium chloride
• Dissolving ammonium chloride in water
• The 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 to 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

Endothermic and Endergonic

An endothermic reaction is a type of endergonic reaction. However, not all endergonic reactions are endothermic. Endothermic reactions involve heat absorption. Other forms of energy that might be absorbed in an endergonic reaction include sound and light.