Presentation on theme: "Ch. 11 Molecular Composition of Gases"— Presentation transcript:
1 Ch. 11 Molecular Composition of Gases If the volume of a gas in the product and reactant of a chemical equation is left at a constant temp. and pressure, then it can be shown as a ration.Avogadro’s principle – says that equal volumes of gases at the same temp. and pressure contain equal numbers of molecules.
2 V = knVolume = constant x number of molesThe volume of a gas is directly proportional to the number of moles of a gas. (At a constant temp. and pressure)Each gas will occupy the same volume at the same temp. and pressure Avogadro’s principle.Standard molar volume of a gas is the volume occupied by 1 mole of a gas at STP 22.4 L
3 ` The molar mass of a gas = 1 mol. of a gas = 22.4 L of a gas at STP. Sample Problem 11-1Sample Problem 11-2Ideal Gas Constant R = PV/nTIdeal gas law – relation between temp., pressure, volume, and # of moles of a gas.Sample Problems 11-3 to 11-5Mass / molar mass = # of molesPV = mRT/M`
4 PV = nRT or PV = mRT/MSample Problem 11-6Density = mass / volumeP = mRT/VMD = MP / RT
5 Stoichiometry of Gases 1. Volume to VolumeVolume A Volume BVolume A x mol. B / mol. A = VOLUME BSample Problem 11-7
6 2. Volume to MassVolume A Mol. A Mol. B mass BUSE n = PV / RT to convert volume to massMol. A x mol. B / mol. A = mol. B x molar mass B = MASS BSample Problem 11-8
7 3. Mass to VolumeMass A Mol. A Mol. B Volume BMass A / Molar mass A x mol. B / mol. A = mol. of BUse V = nRT/P to covert mol. of B into volume of BSample Problem 11-9