Chapter 6

Section 2- changes of state

Kinetic and Potential Energy Kinetic energy- the energy of motion

faster the particles move then the greater the KE Gases have the greatest KE, particles are moving the

fastest in this state of matter Temperature- the average KE of all the particles in the

object

Potential energy- stored energy PE increases when objects are farther apart and

decreases when objects get closer Chemical PE is due to the positions particles relative to

other particles Gases have the most PE

Thermal energy The total potential and kinetic energies of an

object Can change a state of matter by increasing or

decreasing the thermal energy of the object

Solid to liquid or liquid to solid Melting- S to L- thermal energy added Thermal energy and temperature increase until the

melting point. At this point the temperature does not change but

the PE is increasing (particles are moving farther apart)

Freezing is the reverse of melting

Liquid to Gas or Gas to Liquid Liquid to gas- vaporization Vaporization within a liquid is called boiling KE of the particles increases until it reaches

the boiling point Then temperature remains the same but the

potential energy changes Evaporation- occurs on the surface of a liquid Condensation- the reverse process- if a gas

loses enough thermal energy it will become a liquid

Solid to gas or gas to solid Sometimes the intermediate state is not

necessary Dry ice- solid carbon dioxide changes to a gas

with no liquid state This is called sublimation

Deposition- going from gas to solid with no liquid state Frost on the grass

Conservation of mass and Energy Two famous laws Matter can neither be created nor destroyed Matter can change form or state but you are

not losing anything or gaining anything