Presentation on theme: "Molecular Composition of Gases"— Presentation transcript:
1 Molecular Composition of Gases Chapter 12Molecular Composition of Gases
2 Molar Volume of a GasOne mole of a gas has the same volume at STP as any other gas22.4 L / mole at STP
3 Practice ProblemWhat volume would mol of oxygen gas occupy at STP?What about mol of nitrogen gas at STP?
4 Ideal Gas Law PV = nRT n = Number of Moles R = Ideal Gas Constant L . atm/ mol . KV = Volume (must be in liters)P = Pressure (must be in atmospheres)T = Temperature (must be in Kelvin)
5 Practice ProblemWhat is the P (in atm) exerted by a mol sample of nitrogen gas in a 10.0 L container at 298 K?PV = nRT rearranges to P= nRT/ V(0.500 mol)( L .atm/mol .K)(298K)10.0 LPressure = atm
6 Gas Stoichiometry Uses volume-volume calculations (e.g. L L) Liters can be used just like mole to mole ratios in a factor label problem
7 C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(g) Practice ProblemHow many L of oxygen are required for the complete combustion of L of propane?C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(g)Ratio: 5 L O2 makes 1 L C3H80.250 L C3H8 x 5 L O21 L C3H8= 1.25 L O2
8 CaCO3(s) CaO(s) + CO2(g) Practice ProblemHow many grams of calcium carbonate must be decomposed to produce 2.00 L of CO2 at STP?CaCO3(s) CaO(s) + CO2(g)2.00 L CO2 x 1 mol CO2 x 1 mol CaCO322.4 L CO mol CO2x g CaCO31 mol CaCO38.94 g CaCO3
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