Gas Laws

Gases Kinetic Molecular Theory Gases contain particles-- these particles are in constant, random straight line motion. The particles collide with each other and the walls of the container. when the particles collide they transfer energy but the total energy remains constant (what is lost by one particle is gained by another). since the molecules are far apart -- the volume of the individual particle is negligible compared to the total volume of the gas. Gas particles are not attract to each other Pressure Pressure is a measure of force/area P = F/A units mmHg Torr Atmosphere kilo Pascal lb/inch 2 Measuring Pressure Air pressure Barometer vacuum Hg As P inc. the Hg Goes up the tube Measure how high the Hg Rises (mmHg or torr)

Temperature Standard Temperature and Pressure Standard Temp = 0°C or 273 K Standard Pressure = 1atm = 760 mm Hg = 760 torr = kPa Average Kinetic Energy is directly proportional to the Kelvin Temperature Convert °C to K K = °C At absolute zero which is 0 degrees Kelvin or -273°C There is no molecular motion STP Table A

The Gas Laws Boyle’s Law Charles’ Law Gay-Lussac’s Law Avogadro's Principle Combined Gas Law

At constant temperature, the volume of a given mass of gas is inversely proportional to the pressure. P 1 V 1 =P 2 V 2 P V PV =k Inc P dec. V Boyle’s Law

Charles’ Law at constant pressure, the volume of a given mass of gas is directly proportional to absolute temperature (Kelvin). V = k T V T Inc. V, Inc. T V1V1 T1T1 T2T2 V2V2 =

At constant volume,the pressure of a given mass of gas, is directly proportional to absolute temperature (Kelvin). P 1 = P 2 T 1 T 2 P = k T P T Inc. P, Inc. T Gay-Lussac’s Law

Avogadro's Principle equal volume of gases, under the same conditions of temperature and pressure, contain equal number of particles. DIFFERENT MASSES!! Combined Gas Law--Boyle’s and Charles’ laws used together. Reference Tables P 1 V 1 = P 2 V 2 T 1 T 2 If something is held constant, Cross it out

No volume No attraction between particles Follows gas all temps. & pressures. Real Gases & Ideal Gases Do have volume Are Attractions between particles Can condense or solidify *Real gases differ most from ideal gas at low temps. and high pressures.

Real Gases An ideal gas assumes that the molecules have no volume and no attraction to each other. However, real gas molecule do have some volume and are attracted to each other. Real gas behaves ideally 1.High Temp (molecules move fast) 2.Low Pressure (molecules are far apart) Real gases deviate from ideal 1.Low Temp (molecules move slow) 2.High Pressure (molecules are close together) **H and He are most ideal b/c they are small and can move fast. PLIGHT= P-pressure L-Low I- ideal G- gas H- High T- temperature