• Changes of state are?physical changes?that are reversible
• These changes do not change the chemical properties or chemical makeup of the substances involved
• Vaporization?includes?evaporation?and?boiling
• Evaporation?involves the change of liquid to gas, but unlike boiling,?evaporation?occurs only at the surface and takes place at temperatures below the?boiling point
• Boiling?occurs at a specific temperature and takes place when the?vapour pressure?reaches the external atmospheric pressure

State Changes

• The relationship between temperature and energy during state changes can be represented graphically

The relationship between temperature and energy during state changes

• Between 1 & 2, the particles are vibrating and gaining?kinetic energy?and?the temperature rises
• Between 2 & 3, all the energy goes into breaking bonds – there is?no?increase in?kinetic energy?or?temperature
• Between 3 & 4, the particles are moving around and gaining in?kinetic energy
• Between 4 & 5, the substance is boiling, so bonds are breaking and there is?no?increase in?kinetic energy?or?temperature
• From 5 & 6, the particles are moving around rapidly and increasing in?kinetic energy