All Roads Lead to Mole City 1 What Have We Learned Thus Far (10.1) How to convert from molecules to moles/moles to molecules 2 Molecules to Mole …. If you have 7.36 x 1022 molecules of barium sulfate, how many moles of BaSO4 do you have? 7.36 x 1022 molecules BaSO4 1 mole BaSO4 6.02 x 1023 molecules BaSO4 = 0.122 mole BaSO4 Molecules / Avogadro’s # = Moles 3 Moles to Molecules…. 4 If you have 0.632 moles of barium sulfate, how many molecules of BaSO4 do you have? 0.632 moles BaSO4 6.02 x 1023 molecules BaSO4 1 mole BaSO4 = 3.80 x 1023 molecules BaSO4 Moles x Avogadro’s # = Molecules What Have We Learned Thus Far (10.1) How to calculate the molar mass of a compound 5 6 For instance …. What is the molar mass of CuHAsO3? Cu = 1(63.5) H = 1(1.0) As = 1(74.9) O = 3(16.0) = = = = 63.5 g/mol 1.0 g/mol 74.9 g/mol 48.0 g/mol = 187.4 g/mol What Have We Learned Thus Far (10.2) How to convert from grams to moles/moles to grams 7 Grams to Moles …. If you have 12.212 g of CuHAsO3. How many moles do you have? 12.212 g CuHAsO3 1 mole CuHAsO3 187.4 g CuHAsO3 Cu = 1(63.5) = 63.5 H = 1(1.0) = 1.0 As = 1(74.9) = 74.9 O = 3(16.0) = 48.0 = 187.4 g/mol = .065165421 mole CuHAsO3 = .06517 mole CuHAsO3 = 6.517 x 10-2 mole CuHAsO3 Grams / Molar Mass = Moles 8 Moles to Grams …. 9 If you have 1.54 moles of CuHAsO3. How many grams do you have? 1.54 mol CuHAsO3 187.4 g CuHAsO3 = 288.596 g CuHAsO3 1 mole CuHAsO3 Cu = 1(63.5) = 63.5 H = 1(1.0) = 1.0 As = 1(74.9) = 74.9 O = 3(16.0) = 48.0 = 187.4 g/mol = 289 g CuHAsO3 (only 3 sig figs) Moles x Molar Mass = Grams 10 Delayed Objective (10.2) Learn how to convert between moles and volume (L, gas) We will learn this when we derive the Ideal Gas Law in Chapter 14.3, but …… just multiply or divide by 22.4 L All Roads Go Through Mole City 11 Molecule Town Divide by molar mass Mole City Gas Station Multiply by molar mass Gramville Sample mixed mole problem: Molecules to Grams If you have 3.45 x 1025 molecules of NH3, how many grams do you have? 3.45 x 1025 molecules NH3 1 mol NH3 6.02 x 1023 molecules NH3 17.0 g NH3 1 mol NH3 N = 1(14.0) = 14.0 g/mol H = 3(1.0) = 3.0 g/mol molar mass NH3 = 17.0 g/mol = 974.252 g NH3 = 974 g NH3 12 Sample mixed mole problem: Grams to Molecules/Atoms 13 If you have 66.23 g of CO2, how many oxygen atoms do you have? 66.23 g CO2 1 mol CO2 44.0 g CO2 6.02 x 1023 molecules CO2 2 atoms oxygen 1 mol CO2 1 molecule CO2 = 1.8123 x 1024 oxygen atoms C = 1(12.0) = 12.0 g/mol O = 2(16.0) = 32.0 g/mol molar mass CO2 = 44.0 g/mol = 1.81 x 1024 oxygen atoms