The Mole & Stoichiometry!

Important Conversion Factors 1 mole = 6.021023 molecules or atoms = molar mass in grams = 22.4 L (@STP)

Mole Conversions How many grams are in 2.5 moles of CO2? 2.5 mol CO2 44.0 g = 110 g CO2 1 mol

Molar Ratios For reaction calculations, the molar ratio is used. Example: How many moles of nitrogen are needed to react with 9 moles of hydrogen? 2N2(g) +3 H2(g) → 3NH3(g) Given: 9 moles H2, Find moles N2 9 mol H2 x 2 mol N2 = 6 mol N2 3 mol H2 Mole ratio

Stoichiometry Example How many grams of nitrogen are needed to react with 2.0 grams of hydrogen? 2N2(g) +3 H2(g) → 3NH3(g) Given: 2.0 grams H2, Find grams N2 2.0 g H2 x 1 mol H2 2 mol N2 28.0 g N2 = 18.53 g N2 3 mol H2 1 mol N2

Stoichiometry Example For reaction calculations, the molar ratio is used. Example 2: How many grams of nitrogen are needed to react with 2.0 grams of hydrogen using this equation? 2N2(g) +3 H2(g) → 3NH3(g) Given: 2.0 grams H2, Find grams N2 2.0g H2 x g N2 3(2g) 2 (28g) =

Limiting and Excess Reactants Limiting Reactant - limits the amount of product that can be formed and is completely consumed. Excess Reactant - left over when reaction ends

Formulas Empirical : gives the simplest ratio of atoms Molecular: gives the actual number of atoms