States of Matter and Phase Changes “It’s just a phase”

States of Matter Solid, liquid and gas (plasma and BEC). Changes between states are called “phase changes”. Caused by a change of heat or pressure. More often heat.

Molecules are tightly packed together. Particles vibrate in place. Solids Molecules are tightly packed together. Particles vibrate in place. Definite shape and volume. Usually higher densities.

Particles are not so tightly packed. Liquids Particles are not so tightly packed. Molecules move slowly and slide past each other. Medium density. Definite volume, but not a definite shape.

Gases Particles spread out as the container will allow. Particles are moving very quickly (1000 km/sec). Low density. No definite shape or volume.

When a substance changes states. Phase Changes When a substance changes states. During a phase change the temperature does not change, but the amount of energy does.

Transformation of a solid to a liquid. Adding of thermal energy. Melting Transformation of a solid to a liquid. Adding of thermal energy. Ice becoming liquid water.

Transformation of a liquid to a solid. Removing thermal energy. Freezing Transformation of a liquid to a solid. Removing thermal energy. Liquid water becoming ice.

Transformation of a liquid to a gas. Adding of thermal energy. Boiling/Evaporation Transformation of a liquid to a gas. Adding of thermal energy. Liquid water to water vapor (steam).

Transformation of a gas to a liquid. Removing thermal energy. Condensation Transformation of a gas to a liquid. Removing thermal energy. Water vapor becoming liquid water.

Adding thermal energy quickly. Dry Ice does this. Sublimation Transformation of a substance to a gas from a solid state with no liquid transition. Adding thermal energy quickly. Dry Ice does this.

Removing thermal energy quickly. Ex. Frost forming on windows. Deposition When a gas transforms into a solid without transitioning through a liquid state. Removing thermal energy quickly. Ex. Frost forming on windows.

Where does all the energy go? During a phase change energy is added, but the temperature does not increase. The energy goes toward breaking up forces between the particles.