Section 2 Changes of State

What you’ll learn? Define and compare thermal energy. Relate changes in thermal energy to changes of state.

Why is it important? Matter changes state as it heats up or cools down….

New Vocabulary: Thermal energy Temperature Heat Melting Freezing Vaporization Condensation Specific heat

What makes matter changes from one state to another? ENERGY-ability to do work Kinetic Energy Potential Energy - Energy in motion Energy at rest

Thermal Energy? The total kinetic energy of all the particles in a sample of matter. -depends upon the number of particles and amount of energy

Temperature: The average kinetic energy of the individual particle. (degree of coldness and hotness of a body)

Heat: The transfer of thermal energy from a substance at a temp. to a temp.

Specific Heat? The amount of heat that is required to raise the temperature of 1 gram of a substance to 1 ° C.

CHANGES BETWEEN SOLID & LIQUID STATE MELTING: Change from solid to liquid Melting point of H2O - 0°C FREEZING: Change from liquid to solid Freezing point of H2O- 0°C By absorbing & releasing heat

MELTING POINT FREEZING POINT - temp. at which a substance changes from solid to liquid. FREEZING POINT - temp. at which a substance changes from a liquid to solid.

2. CHANGES BETWEEN THE LIQUID AND GAS STATE BOILING Takes place below the surface of a liquid. Boiling Point: -temp. at which liquid boils Boiling point of H20- 100°C EVAPORIZATION -Takes place at the surface of the liquid. VAPORIZATON: the change from a liquid to gas. 2 TYPES; BOILING EVAPORIZATION

BOILING EVAPORATION

CONDENSATION -change from gas to liquid Formation of droplets Water vapor in the atmosphere condenses to water droplets (rain).

3.CHANGES BETWEEN SOLID AND GAS STATE SUBLIMATION -change from solid to gas without becoming liquid. Ex. Dry ice (solid of C02) DEPOSITION -change from gas to solid

IN SUMMARY….