Is Vaporization Exothermic or Endothermic?

Vaporization is an example of an endothermic reaction. In chemistry, vaporization is defined as the transformation of a solid or liquid into gas. This is caused by either evaporation or boiling.

Exothermic and endothermic reactions both cause some type of energy level differences. In an exothermic reaction, energy is released in the form of heat. As chemical bonds are formed, energy is released. An example is water turning into ice. Chemical bonds form and release energy to create ice crystals.

An endothermic reaction, however, is the opposite. Here, the energy is absorbed in the form of heat. When a chemical bond is broken, the energy used creates an endothermic reaction. Changing ice into water, then vapor, requires the chemical bonds to be broken. That is why vaporization is an example of an endothermic reaction. Energy is used to break chemical bonds to cause the solid (ice) or liquid (water) to transform into vapor.

Other examples of an endothermic process are:

  • Baking cookies
  • Splitting molecules
  • Separating pairs of ions
  • Melting solids

Some examples of endothermic reactions include:

  • Mixing ammonium nitrate and water
  • Mixing potassium chloride with water
  • Dissolving ammonium chloride in water
  • Reacting sodium carbonate with ethanoic acid
  • Photosynthesis, because carbon dioxide reacts with chlorophyll, water and energy to create oxygen and glucose