Additional Gas Laws Dalton’s Law of Partial Pressures, Ideal Gas Law, and Gas Stoichiometry

10-3 Learning Targets 1.To describe the process and implications of collecting a gas “over water” 2.To calculate the pressure of a “dry gas” 3.To calculate the variables of a gas under Ideal Conditions 4.To calculate a gas’s Molar Mass or Density.

Dalton’s Law of Partial Pressures P total =

Dalton’s Law of Partial Pressures Setup of Gas Collection Over Water

Dalton’s Law of Partial Pressures What’s in the collection tube?

Dalton’s Law of Partial Pressures Why is there water vapor (gas) inside of the collection tube? How does temperature affect the collection?

Dalton’s Law of Partial Pressures P total = P gas + P water

Dalton’s Law of Partial Pressures A sample of hydrogen gas is collected over water in lab at 25 o C. The barometric pressure is100.3 kPa. Calculate the pressure of the dry gas.

Deriving a New Gas Law R PV = nRT

Ideal Gas Law PV = nRT R = L∙atm/mol∙K R = L∙mmHg/mol∙K

Ideal Gas Law 6.2 liters of an ideal gas are contained at 3.0 atm and 37 °C. How many moles of this gas are present?

Gas Equations and Known Variables Standard Molar Volume ◦ 1 mole of a gas at STP occupies a volume of 22.4 L Gas Density  Amount of gas (g) per volume (L)  Measured in g/L Known Equations: ◦ PV = nRTMM = m/n D= m/V ◦ R = L∙atm/mol∙ K = 62.4 L∙mmHg/mol∙K

Ideal Gas Law Variations ◦ Reworked Equations: Molar MassDensity

Molar Mass 1.) A g sample of gas has a volume of 200. mL at STP. What is the molar mass of the gas?

Molar Mass 2.) At 28°C and 740. mm Hg pressure, 1.00 L of an unknown gas has a mass of 5.16 g. What is the molar mass of the gas?

Density 3.) What is the density of a sample of ammonia gas if the pressure is 705 mm Hg and the temperature is 63.0°C?

10-4 Learning Targets Calculate the volume of a gas involved in a chemical reaction under given conditions (not STP)

Gas Stoichiometry Gas Stoichiometry: calculating amount of gas produced or used in a chem. rxn. Semester 1: ◦ Use molar volume at STP: 22.4 L = 1 mole Semester 2: ◦ Use Ideal Gas Law to determine volumes of gas in rxns under varying pressures and temperatures

Gas Stoichiometry 1.) What volume, in liters, of SO 2 at 0 o C and 1 atm is produced by 18.0 grams of sulfur? S (s) + O 2 (g)  SO 2 (g)

Gas Stoichiometry 2.) How many liters of hydrogen at 35°C and 745 mm Hg are needed to react completely with 875 g of tungsten (VI) oxide? WO 3 (s) + 3 H 2 (g)  W (s) + 3 H 2 O (l)

Gas Stoichiometry 3.) How many liters of CO at 27°C and 188 mm Hg can be produced from the burning of 65.5 g of carbon? 2 C (s) + O 2 (g)  2 CO (g)