B. Heating Curves Melting - PE  Solid - KE  Liquid - KE  Boiling - PE  Gas - KE 

Heating Curve = Energy Sponge Graph  All of the universe and its substances within in are ENERGY SPONGES  At anytime a sustance is either absorbing energy or releasing energy (just like a sponge with water) Temperature Heat Energy Added (calories or joules) Larger Energy Sponge for Vaporization Small Sponge for Melting Squeeze Me!

B. Heating Curves  Temperature Change change in KE (molecular motion) depends on heat capacity  Heat Capacity energy required to raise the temp of 1 gram of a substance by 1°C “Volcano” clip - water has a very high heat capacity

B. Heating Curves  Phase Change change in PE (molecular arrangement) BUT the temp remains constant until phase change is complete  Heat of Fusion (  H fus = 80 cal/g water) energy required to melt 1 gram of a substance at its m.p. or energy released by 1 gram freezing at f.p.

B. Heating Curves  Heat of Vaporization (  H vap =540cal/g water) energy required to boil 1 gram of a substance at its b.p. or energy released when 1 gram of vapor condensed into a liquid usually larger than  H fus …why?  EX: sweating, steam burns, the drinking bird

C. Phase Diagrams  Show the phases of a substance at different temps and pressures.

Enthalpies of Vaporization (Heat of Vap) of common substances measured at their respective normal boiling points: Compound Heat of vaporization (kJ /mol) kJ /mol Heat of vaporization (kJ/ kg) kJ/ kg Ammonia Butane Ethanol Hydrogen Methane Methanol Propane Phosphine Water Water is also commonly expressed as calories per gram