Handout 10 Assignment 1. What volume of oxygen at STP is needed to completely burn 15.0 g of methanol (CH3OH) in a fondue burner? (CO2 + H2O are products) [15.7 L O2 ] 2CH3OH + 3O2 2CO2 + 4H2O Volume O2= 15.0 g x 1 mol x 3 mol = 0.702028081 mols 32.05 g 2 mol PV=nRT V=nRT/P V= (0.702028081 mols)(8.314)(273 K) 101.325 kPa V=15.7 L of O2 2. When sodium chloride is heated to 800°C it can be electrolytically decomposed into Na metal & chlorine (Cl2) gas. What volume of chlorine gas is produced (at 800°C and 100 kPa) if 105 g of Na is also produced?[204 LCl2 ] 2NaCl 2Na + Cl2 Volume Cl2= 105 g x 1 mol x 1 mol= 2.283601566 mols 22.99 g 2 mols PV=nRT V=nRT/PV= (2.283601566 mols)(8.314)(1073 K) 100 kPa V= 204 L Cl2 3. What mass of propane (C3H8) can be burned using 100 L of air at SATP? Note: 1) air is 20% O2, so 100 L of air holds 20 L O2, 2) CO2 and H2O are the products of this reaction. [7.1 g C3H8 ] C3H8 + 5O2 3CO2 + 4H2O PV=nRT n=PV/RT n=(100 kPa)(20 L) (8.314)(298 K) n=0.807241928 mols O2 x 1 mol x (44.11 g) = 7.1 g C3H8 5 mol 1 mol 4. A 5.0 L tank holds 13 atm of propane (C3H8) at 10°C. What volume of O2 at 10°C & 103 kPa will be required to react with all of the propane? [320 L O2 ] C3H8 + 5O2 3CO2 + 4H2O PV=nRT n=PV/RT n=(1317.225)(5.0 L) (8.314)(283) n=2.79919197318 mols x 5 mols =13.99598659 mols of O2 1 mols PV=nRT V=nRT/P V= (13.99598659 mols)(8.314)(283K) 103 kPa V=320 L O2 5. Nitroglycerin explodes according to: 4 C3H5(NO3)3(l) 12 CO2(g) + 6 N2(g) + 10 H2O(g) + O2(g) a) Calculate the volume, at STP, of each product formed by the reaction of 100 g of C3H5(NO3)3. [29.6 L CO2; 14.8 L N2; 24.7 L H2O, 2.47 L O2 ] 4C3H5(NO3)3 12CO2 + 6N2 + 10 H2O + O2 a) 100 g x 1 mol x 12 mol = (1.320945797 mols)(8.314)(273 K) = 29.6 L CO2 227.11 g 4 mol 101.325 kPa 100 g x 1 mol x 6 mol = (0.660472898 mols)(8.314)(273 K) = 14.8 L N2 227.11 g 4 mol 101.325 kPa 100 g x 1 mol x 10 mol = (1.100788164 mols)(8.314)(273 K) = 24.7 L H2O 227.11 g 4 mol 101.325 kPa 100 g x 1 mol x 1 mol = (0.110078816 mols)(8.314)(273 K) = 2.47 L O2 227.11 g 4 mol 101.325 kPa b) 200 g of C3H5(NO3)3 is ignited (and completely decomposes) in an otherwise empty 50 L gas cylinder. What will the pressure in the cylinder be if the temperature stabilizes at 220°C? [523 kPa] b) 2.64 mols CO2 1.32 mols N2 2.20 mols H2O 0.220 mols O2 Total mols= 6.38 mols PV=nRT P=nRT/V P= (6.38 mols)(8.314)(493 K) 50 L P= 523 kPa
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