What happens to molecules as the temperature increases? Kinetic Energy Increases, they move faster What are on the axis of a phase change diagram? Temperature and Pressure What are the three phases that a substance passes through? Solid, liquid, gas Do all phase change diagrams look the same, why? No, different substances change phases under different conditions

 The purpose of a heating curve is to see the temperature change as heat (energy) is added to a system.  From a heating curve you can get a substances melting/freezing point and boiling point

 As heat is added to the solid the temperature increases.  When it reaches the melting point the temperature remains constant until all of the solid has become liquid.

 Once the substance has all become liquid the temperature will begin to rise again.  The temperature rises until it reaches the boiling point.  Again, the temperature will remain constant until all of the liquid has become vapor/gas

Solid - KE  Melting - PE  Liquid - KE  Boiling - PE  Gas - KE 

Cooling curve is the same thing as a heating curve, just in the opposite direction. In this graph we start at high temperatures and get lower. Remember that melting point occurs at the same temperature as freezing point.

In science we typically use two equivalent units of temperature, degrees Celsius and kelvin. The Celsius scale sets the freezing point of water at 0 0 C and the boiling point at C. The Kelvin scale sets freezing at kelvin and boiling at kelvin. A change of one degree is equal on each scale. The zero point on the Kelvin scale is considered absolute zero. Since the scales are the same all you have to do to convert from one to the other is add/subtract C = K