SOLID - LIQUID - GAS

These are the 3 common "States of Matter" that virtually all students are aware of and have little trouble identifying. A rock is matter in the solid state; water is matter in the liquid state, and air is matter in the gas state. (However, the observant student might wonder about matter like peanut butter, jelly, or whipped cream! What do you think?)

Matter under extremely high temperatures can also exist in the "plasma" state. The hydrogen atoms that make up the stars including our Sun exist in the super-high energy

plasma state.

The "States of Matter" are conditions of matter that are dependent on

relative temperature and pressure.

"Phase Changes" occur when matter changes state through heat absorption or heat loss

or through pressure changes. Most phase changes have common names that you will be sure to recognize:

HEATING (+H) Increasing the temperature of matter can result in

Melting (S> L), Evaporation (L> G), Vaporization (L> G), or Sublimation (S> G).

COOLING (-H) Decreasing the temperature of matter can result in

Freezing (L> S), Condensation (G> L), or Sublimation (G> S).

Increasing pressure can change matter in the gas state into the liquid state

Decreasing pressure can change matter in the liquid state into the gas state

When propane gas is forced under pressure in a B-B-Q tank the C3H8 molecules

are squeezed together into the liquid state. When the valve is opened, the liquid

propane is de-pressurized allowing it to instantly vaporize (boil) into the gas

state (C3H8 molecules move far apart!).

Matter cannot be classified by it's "state" because phase changes do not alter the

chemical identity of matter. Phase changes can only alter the distance between

molecules and are examples of physical change.

ICE is H2O molecules in the SOLID state;

WATER is H2O molecules in the LIQUID state

WATER VAPOR is H2O molecules in the GAS state