Warm-Up 9/25/13 Sketch what molecules look like in the following situations. Include arrows to show relative motion. Solid, 20°C Liquid, 50°C Liquid, 90°C Gas, 120°C

Phase Changes Wednesday, 9/25/13

Changing State Requires Energy! Changes of state occur with a change in temperature or pressure Particles of a substance overcome (or succumb to) intermolecular attraction

MUCH motion/vibration = MUCH Kinetic Energy = MUCH associated heat E More motion/vibration = More Kinetic Energy = More associated heat E Little motion/vibration = Little Kinetic Energy = Little associated heat E

Melting Solid state to liquid state Solid particles gain energy and are able to break apart from one another Energy Required: “Heat of Fusion” Opposite: Freezing

Evaporating Liquid state to gas state Liquid particles gain enough energy to escape into the vapor state Energy Required: “Heat of Vaporization” Opposite: Condensing

Boiling will happen when the downward atmospheric pressure is equal to (or less than) the upward vapor pressure from the liquid

Sublimation Solid state to gas state Requires rapid change in temperature or pressure Opposite: Deposition

Your Job Complete questions 1 and 2 in the States of Matter and Phase Changes packet…DUE TOMORROW. Matter Project revisions due Monday QUIZ Monday on Physical/Chemical Change and Phase Changes