9.1/9.2 Stoichiometric Calculations Ch. 9 Stoichiometry 9.1/9.2 Stoichiometric Calculations

Stoichiometry Deals with mass relationships between reactants and products in a chemical reaction Can be a conversion between two reactants, reactants and products or two products Review Conversion Basics: Should you write numbers or units first? What do you use to convert between g and moles of a compound? In this conversion, what number goes next to mol?

Moles A ⇄ Moles B to get mole ratios, you must have a balanced chemical equation tells us the relative amounts of each type of reactant needed to produce each product used to convert between moles of one substance to moles of another substance

Example Al2O3(l)  Al(s) + O2(g) If the reaction begins with 13.0 mol of Al2O3, how many moles of Al will be created?

Example If we want the reaction to produce 28.0 moles of O2, how many moles of Al2O3 should you begin the reaction with? How many moles of Al will you also end with?

Grams ⇄ Moles use molar mass and mole ratio Grams A  Moles B grams A  moles A using molar mass moles A  moles B using mole ratio Moles A  Grams B moles B  grams B using molar mass

Example 2 If you began the reaction with 2.00 g of Al2O3, how many moles of O2 will you end up with? g  mol using molar mass mol  mol using mole ratio

Example 2 If the reaction produces 23.7 mol Al, how many grams of O2 should it also end with? mol  mol mol  grams

Grams A ⇄ Grams B use molar mass twice grams A moles A using molar mass moles A  moles B using mole ratio moles B  grams B using molar mass

Example 3 If you begin the reaction with 14.45 g Al2O3, how many grams of Al would it end with? grams Al2O3  mol Al2O3 using molar mass mol Al2O3  mol Al using mole ratio mol Al  grams Al using molar mass

Example 3 If the mass of O2 ended up being 21.9 g, how many grams of Al2O3 did the reaction begin with? grams O2  mol O2 using molar mass mol O2  mol Al2O3 using mole ratio mol Al2O3  grams Al2O3 using molar mass