Presentation on theme: "Phase of Matter. Phases of Matter Gases indefinite volume and shape, low density. Liquids definite volume, indefinite shape, and high density. Solids."— Presentation transcript:
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 + 273 55 °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 = 4.186 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