Stoichiometry Moles to Moles

Moles to Moles Stoichiometry describes the relationships between reactants and products in chemical equations A balanced chemical equation is the simplest “recipe” for a particular reaction

Moles to Moles CH4 + 3 CuO 3 Cu + 2 H2O + CO 1 molecule of methane reacts with 3 formula units of copper (II) oxide to form 3 atoms of copper, 2 molecules of water, and 1 molecule of carbon monoxide But this is just the basic recipe. We can multiply the recipe many times if we wish, and the relationship between (ratio) ingredients does not change

Moles to Moles CH4 + 3 CuO 3 Cu + 2 H2O + CO 1 molecule 3 units Basic 1 molecule 3 units 3 atoms 2 molecule

Moles to Moles CH4 + 3 CuO 3 Cu + 2 H2O + CO 1 molecule 3 2 Basic 1 molecule 3 units atoms 2 molecule x 2 2 molecules 6 4 molecule 2 molecule

Moles to Moles CH4 + 3 CuO 3 Cu + 2 H2O + CO 1 3 3 atoms 2 1 molecule Basic 1 molecule 3 units 3 atoms 2 1 molecule x 12 12 molecule 36 36 atoms 24 molecule dozen

Moles to Moles 1 mole 3 moles 2 moles 1 molecule 3 3 atoms 2 molecule CH4 + 3 CuO 3 Cu + 2 H2O + CO Basic 1 molecule 3 units 3 atoms 2 molecule x 6.02 x 1023 6.02 x 1023 molecules 1.81 x 1024 atoms 1.20 x 1024 1 mole 3 moles 2 moles

Moles to Moles CH4 + 3 CuO 3 Cu + 2 H2O + CO Equations usually discussed using number of moles of each chemical involved (1 mol CH4, 3 mol CuO, 3 mol Cu etc.) As long as ratios are the same, any amount of reactant can be used with exact same results

Moles to Moles How many moles of aluminum oxide will you produce if you start with 5.40 mol of aluminum? 4 Al + 3 O2 2 Al2O3 Easy to solve: just keep ratios the same! 4 mol Al : 2 mol Al2O3

Moles to Moles = 4 Al + 3 O2 2 Al2O3 How many moles of aluminum oxide will you produce if you start with 5.40 mol of aluminum? 4 Al + 3 O2 2 Al2O3 mole ratio 4 mol Al : 2 mol Al2O3 5.40 mol Al 2 mol Al2O3 = 2.7 mol Al2O3 4 mol Al

Moles to Moles These problems can ONLY be done using mole ratios CAN NOT do the same problem using mass ratios the coefficients in a chemical equation represent molar quantities (numbers of things), not the mass of things

Moles to Moles = 4 Al + 3 O2 2 Al2O3 How many moles of oxygen will you need to produce 18 mol of aluminum oxide? 4 Al + 3 O2 2 Al2O3 mole ratio 3 mol O2 : 2 mol Al2O3 18 mol Al2O3 3 mol O2 = 27 mol O2 2 mol Al2O3

Start in Class Finish as H.W PRACTICE PROBLEMS Start in Class Finish as H.W In pick-up box

Grams to Grams Chemicals used by mass, not by moles Same problems can be done, just have to covert grams to moles, and then moles back to grams

Grams to Grams = 4 Al + 3 O2 2 Al2O3 How many GRAMS of aluminum oxide will you produce if you start with 92 GRAMS of aluminum? 4 Al + 3 O2 2 Al2O3 mole ratio 4 mol Al : 2 mol Al2O3 92 g Al 1 mol Al 2 mol Al2O3 102 g Al2O3 = 173.78 g Al2O3 27 g Al 4 mol Al 1 mol Al2O3

Grams to Grams = 4 Al + 3 O2 2 Al2O3 How many GRAMS of oxygen will you need to produce 219 GRAMS of aluminum oxide? 4 Al + 3 O2 2 Al2O3 mole ratio 3 mol O2 : 2 mol Al2O3 219 g Al2O3 1 mol Al2O3 32 g O2 3 mol O2 = 103.1 g O2 102 g Al2O3 2 mol Al2O3 1 mol O2

GRAMS #1 GRAMS #2 MOLES #2 MOLES #1 MOLE:RATIO