Stoichiometric Calculations Stoichiometry Stoichiometric Calculations C. Johannesson

Proportional relationships To make a PBJ sandwich, you need 2 slices of bread, 2 tablespoons of peanut butter, and 2 tablespoons of jelly. If you have 15 slices of bread, and plenty of peanut butter and jelly, how many sandwiches could you make? C. Johannesson

Proportional Relationships Stoichiometry mass relationships between substances in a chemical reaction based on the mole ratio Mole Ratio indicated by coefficients in a balanced equation 2 Mg + O2  2 MgO C. Johannesson

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Mole map C. Johannesson

Mole Map / Foldable C. Johannesson

Stoichiometry problems C. Johannesson

Stoichiometry Steps 4. Check answer. 1. Write a balanced equation. 2. Identify known & unknown. 3. Line up conversion factors. Mole ratio - moles  moles Molar mass - moles  grams 4. Check answer. C. Johannesson

Mole to mole 2KClO3  2KCl + 3O2 9 mol O2 2 mol KClO3 3 mol O2 = 6 mol How many moles of KClO3 must decompose in order to produce 9 moles of oxygen gas? 2KClO3  2KCl + 3O2 ? mol 9 mol 9 mol O2 2 mol KClO3 3 mol O2 = 6 mol KClO3 C. Johannesson

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Mole to gram How many grams of calcium nitride are produced with 2.5 moles of calcium? 3Ca + N2  Ca3N2 2.5 mol Ca 1 mol Ca3N2 148.26 g Ca3N2 1 mol Ca3N2 3 mol Ca = 123.55 g Ca3N2 C. Johannesson

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Example Calculate the number of moles of ethane (C2H6) needed to produce 10 g of water. 2C2H6 + 7O2  4CO2 + 6H2O 10 g H2O 1 mol H2O 2 mole C2H6 = 0.19 mol C2H6 18.02 g H2O 6 mole H2O C. Johannesson

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D. Stoichiometry Problems How many grams of silver will be formed from 12.0 g copper? Cu + 2AgNO3  2Ag + Cu(NO3)2 12.0 g ? g 12.0 g Cu 1 mol Cu 63.55 g Cu 2 mol Ag 1 mol Cu 107.87 g Ag 1 mol Ag = 40.7 g Ag C. Johannesson

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