Gas Stoichiometry PDF

Chemistry Unit 2 Gas Stoichiometry Lesson 4: Teacher’ Copy Table of contents 01 02 Gases with the Gas Same temperature Stoichiometry: All and pressure other examples 0...

Chemistry Unit 2 Gas Stoichiometry Lesson 4: Teacher’ Copy Table of contents 01 02 Gases with the Gas Same temperature Stoichiometry: All and pressure other examples 0 03 Gas Stoichiometry 4 Gas Stoichiometry Map: Gas to Gas Map: mixed states of matter  01 Gases with the same temperature and pressure  Stoichiometry of gases using the ratio of coefficients in a balanced chemical equation in order to determine a quantity of reactant or product given that one of these is a gas If we know that temperature and pressure are constant, we can use the stoichiometric ratios to determine the volumes of gases reacted or produced -- this only works with gases to gases At STP AT SATP 22.4 L gas= 1 mol gas 24.5 L gas = 1mol gas  Gases at the Same Temperature and Pressure For gases at the same temperature and pressure, the stoichiometric ratios are the same at the volume ratios N2(g) + 3 H2(g) --> 2NH3(g) Coefficient 1 3 2 Molar ratio 1 3 2 Volume ratio at 22.4 L 67.2 L 44.8 L STP Volume ratio at 24.5 L 73.5 L 49.0 L SATP Volume ratio 1 3 2 Example 1: Volume of a gas to volume of a gas What volume of oxygen is needed for the complete combustion of 4.00 L of propane (C3H8) given that the pressure and temperature remain constant? C3H8 (g) + 5O2 (g) → 3CO2(g) + 4H2O(g) 4.00 L ?L Stoichiometric ratio -- can be used to determine volumes of gases, when pressure and temperature are constant  02 Gas Stoichiometry: All other examples  Example 2: Volume of a gas to a non-gas at STP How many grams of KClO3 are req’d to produce 9.00 L of O2 at STP? 2KClO3(s) → 2KCl(s) + 3O2(g) ? 9.00 L At STP, 1 mol of any gas = 22.4 L of volume You cannot find the volume of this substance because it is not a gas  Example 3: Non-STP What volume of CO2 forms from 5.25 g of CaCO3 at 103 kPa & 25ºC? CaCO3(s) → CaO(s) + CO2(g) Looking for volume from grams: start with stoichiometry to find moles of CO 2(g) Use PV=nRT to solve for volume Example 4: Non-STP How many grams of Al2O3 are formed from 15.0 L of O2 at 97.3 kPa & 21°C? 4 Al (s)+ 3 O2(g) → 2 Al2O3(s)  Example 5: Different Conditions What volume of H2 at STP will be needed to produce 800 L of ammonia, measured at 55oC and and 0.900 atm? N2(g) + 3 H2(g) → 2 NH3(g) Step 1: Find mols of NH3 using PV=nRT Step 2: Stoichiometry Example 5: Different Conditions What volume of H2 at STP will be needed to produce 800 L of ammonia, measured at 55oC and and 0.900 atm? N2(g) + 3 H2(g) → 2 NH3(g) Step 3: Find Volume at STP using Step 3: Find Volume at STP using molar volume PV=nRT 03 Gas Stoichiometry: Gas to Gas  o T= C + 273.15 Depending on the significant figures of the thermometer reading, the decimals may be needed. Gas 04 Stoichiometry: mixed states of matter