Stoichiometry

Stoichiometry Basics Stoichiometry is the study of the quantitative relationships that exist in chemical formulas and balanced chemical equations. Stoichiometry allows us to calculate the amounts of substances that are related by a balanced chemical equation.

Do You Remember? 4 Fe + 3 O2 → 2 Fe2O3 8 Fe + 6 O2 → 4 Fe2O3 4 mol Fe + 3 mol O2 → 2 mol Fe2O3 0.24 mol Fe + 0.18 mol O2 → 0.12 mol Fe2O3

Interpreting Balanced Equations Balance the equation... Cu + AgNO3 → Cu(NO3)2 + Ag 2 This means that 1 mole of copper reacts with 2 moles of silver nitrate to form 1 mole of copper (II) nitrate and 2 moles of silver.

Balance the equation... Mole - Mole Problems Li + N2 → Li3N 2 6 2 6 How many moles of Li3N can be produced if 3.00 moles of lithium reacts completely with nitrogen?

How many moles of N2 are required to react with 7.2 moles of Lithium? Review Example Li + N2 → Li3N 2 6 How many moles of N2 are required to react with 7.2 moles of Lithium?

2 H3PO4 + 3 Mg(OH)2 → Mg3(PO4)2 + 6 H2O Mass Volume Moles in moles moles moles moles moles moles moles moles moles moles moles moles moles mole moles 2 H3PO4 + 3 Mg(OH)2 → Mg3(PO4)2 + 6 H2O The balanced chemical equation is the gateway. Moles out Mass Volume

The balanced chemical equation is the gateway. 2 H3PO4 + 3 Mg(OH)2 → Mg3(PO4)2 + 6 H2O Moles in Mass Volume Moles out moles moles moles moles moles moles moles moles moles moles moles moles moles mole moles Molar mass or Formula mass Molar volume Molar mass or Formula mass Molar volume

Mass - Mass Conversions How many grams of SnF4 can be formed from 12.8 g of HF? Sn + 4HF → SnF4 + 2H2

Mass - Volume Problems 2 Mg + O2 → 2 MgO How many liters of O2(g) are needed at STP to burn 60.0 g of magnesium? 2 Mg + O2 → 2 MgO

Volume - Volume Problems How many liters of H2O(g) can be formed from 48.9 L of CH4(g) at STP? CH4 + 2 O2 → CO2 + 2 H2O Notice that numerically the first ratio and the third ratio cancel out. For vol/vol problems the mole ratio is sufficient.

Maximum labeling - C6H12O6 → 2 C2H6O + 2 CO2

Minimum labeling - C6H12O6 → 2 C2H6O + 2 CO2

(and,… just what is a limiting reactant?) Limiting Reactants Under what conditions do we need to be concerned about limiting reactants? (and,… just what is a limiting reactant?)

What mass of iron (IV) sulfide is formed when 20 What mass of iron (IV) sulfide is formed when 20.0 g of iron reacts with sulfur? 4 Fe + S8 → 4 FeS2

What mass of iron (IV) sulfide is formed when 20 What mass of iron (IV) sulfide is formed when 20.0 g of sulfur reacts with iron? 4 Fe + S8 → 4 FeS2

Summary 4 Fe + S8 → 4 FeS2

What happens at this point? 4 Fe + S8 → 4 FeS2 The reaction STOPS!

Since there is some iron left over we say it is in excess. Since sulfur causes the reaction to stop we call sulfur the limiting reactant in this reaction. Since there is some iron left over we say it is in excess.

2Al(OH)3 + 3H2CO3 → Al2(CO3)3 + 6H2O What is the limiting reactant in the following reaction? 2Al(OH)3 + 3H2CO3 → Al2(CO3)3 + 6H2O

2Al(OH)3 + 3H2CO3 → Al2(CO3)3 + 6H2O What is the limiting reactant in the following reaction? 2Al(OH)3 + 3H2CO3 → Al2(CO3)3 + 6H2O

2Al(OH)3 + 3H2CO3 → Al2(CO3)3 + 6H2O What is the limiting reactant in the following reaction? 2Al(OH)3 + 3H2CO3 → Al2(CO3)3 + 6H2O

2Al(OH)3 + 3H2CO3 → Al2(CO3)3 + 6H2O What is the limiting reactant in the following reaction? 2Al(OH)3 + 3H2CO3 → Al2(CO3)3 + 6H2O