Gases

Gases and Pressure Pressure is the measure of the amount of force (Newton) per unit area (cm2) Pressure can be measured in several different units Torr or mmHg kPa Atm 1atm = 101.3 kPa = 760mmHg (or Torr)

Pressure Conversions

STp and Dalton’s Law Standard Temperature and Pressure 0ºC and 1 atm Dalton’s Law of Partial Pressure The sum of the pressures of all the gases in a system is equal to the total pressure of the system

Dalton’s Law of Partial Pressure

Boyle’s Law Boyle’s Law Robert Boyle States that at a constant temperature, the volume of a gas varies inversely with pressure V1 x P1 = V2 x P2

Boyle’s law

Charles’s Law Charles’s Law Jacques Charles States that at a constant pressure and mass, the volume of a gas and the temperature are directly proportional V1 / T1 = V2 / T2 Temperature must be in Kelvins

Charles’s Law

Gay-Lussac’s Law Gay-Lussac’s Law Joseph Gay-Lussac States that at a constant volume, the pressure of a gas and the temperature are directly proportional P1 / T1 = P2 / T2 Temperature must be in Kelvins

Gay-Lussac’s Law

Combined Gas Law The combined gas law combines all three gas laws (V1 x P1) / T1 = (V2 x P2) / T2 Temperature must be in Kelvins

Gas Stoichiometry and Ideal Gas Law Gay-Lussac’s Law of Combining Volumes States that when temperature and pressure are held constant, volumes of combined gases can be expressed as simple whole number ratios Avogadro’s Law State that equal volumes of gases at the same temperature and pressure contain equal number of particles These two laws establish a relationship between gas volumes and the number of moles

Gas Stoichiometry Relationship between volume and moles 1 mol = 22.4 L of gas @ STP = 6.02 x 1023 particles = molar mass (grams)

Gas Stoichiometry

Ideal Gas Law Factors in not only pressure, temperature, and volume but also the number of particles (moles) The amount of particles in a system can also affect the other variables as well PV = nRT P = pressure (kPa) V = volume (L) n = number of moles R = Ideal gas constant (8.314 L x kPa/mol x K) T = Temperature (Kelvins)

Ideal Gas Law