THE CHANGES IN MATTER / THE CHANGES IN ENERGY

Physical changes can also involve energy exchanges. Almost all changes of matter involve energy, so it is important to examine basic concepts and relationships of energy and how it is associated with matter in motion and with the potential to move matter. As substances get warmer the vibration of its molecules increases. If there is enough vibration to overcome the rigid arrangement of molecules in a solid, then the arrangement falls apart and the substances changes state to a liquid. This is what happens to molecules when a change of state occurs...How does energy fit in?

Interactions between matter always involve changes in energy. When wood burns, the energy held in the chemical bonds is converted to light and heat.

Explain the evaporation of alcohol:

The heat energy transferred by conduction from my hand to the alcohol increased the motion of the molecules in alcohol. These molecules spread apart as the liquid changed to a gaseous state.