The three changes of state during which energy is absorbed are:
1. Change from solid to liquid - Melting.
2. Change from liquid to gas - Vaporization
3. Change from solid to gas - Sublimation
All these changes of state require heat energy to break the attractive forces that hold the particles of the molecules together, so that they can move into more disorderly states. For instance, when heat is applied to a solid, the solid absorbs the heat and use it to break the attractive forces that are holding the molecules of the solid together. At a particular temperature, the attractive forces will be completely overcome and the solid framework will collapse, thus leading to the melting of the solid.
Three changes of state during which energy is absorbed are :
1. solid to liquid - heat goes into the solid as it melts.
2. Liquid to gas - Heat goes into the liquid as it vaporizes. This change of state includes boiling and evaporation.
3.Solid to gas - this is sublimation. Heat goes into the solid as it sublimates.
Change in phase of a material or substance always involves a change of heat whereby heat energy is either absorbed into the material or given up from the material
