Phase of Matter

Phases of Matter Gases indefinite volume and shape, low density. Liquids definite volume, indefinite shape, and high density. Solids definite volume and shape, high density Solids and liquids have high densities because their molecules are close together.

Temperature Measured in Celsius (°C) All math is done in Kelvin (K) K = °C °C = _________K 350 K = _________°C Standard Temp. – refers to 0 °C Absolute Zero – 0 K – lowest temp possible

Kinetic Theory uKinetic theory says that molecules are in constant motion.  Perfume molecules moving across the room are evidence of this. uHowever, not all molecules in a sample will move at the same speed

Kinetic Energy and Temperature Kinetic energy is the energy of motion Temperature is a measure of the Average kinetic energy of the molecules of a substance. Higher temperature faster molecules. At absolute zero (0 K) all molecular motion would stop.

Kinetic Energy % ofMolecules% ofMolecules High temp. Low temp.

Kinetic Energy % ofMolecules% ofMolecules High temp. Low temp. Average kinetic energies are temperatures

The average kinetic energy is directly proportional to the temperature in Kelvin If you double the temperature (in Kelvin) you double the average kinetic energy. If you change the temperature from 300 K to 600 K the kinetic energy doubles. Temperature

Heat Not the same as temperature Heat is the total kinetic energy of all particles in a substance Heat flows in or out of a substance until temperature is equalized Heat always flows from high to low temperature

Heat Total kinetic energy of the molecules in a substance Units Calorie – amount of heat needed to raise the temp of 1g of water 1  C Joule – metric unit of heat 1 cal = J 5.75 cal = __________J 15.5 J = __________cal

Phase Changes Solid Liquid Gas Melting Vaporization CondensationFreezing

Liquid Sublimation Melting Evaporation Resublimation Condensation Solid Freezing Gas

Heat is either added or removed during phase changes For each phase change below, will heat be absorbed or released. Describe as endothermic or exothermic. - freezing - melting - evaporating - condensing - sublimation - resublimation

Entropy Disorder of particles (randomness) In nature all systems tend to disorder, increase in entropy