Stoichiometry

What is stoichiometry? Composition stoich – deals with mass relationships of elements in compounds (review Ch 3) Reaction stoich – deals with relationships between reactants and products

Reaction Stoichiometry 4 types of problems

Type 1 Given and unknown quantities in moles Amount of given (in mol)  Amount of unknown (in mol)

Type 2 Given amount is in moles and unknown is mass in grams Amount given (in mol)  amount unknown (in mol)  mass unknown (in g)

Type 3 Given is amount in grams and unknown is amount in moles mass given (in g)  amount given (in mol)  amount unknown (in mol)

Type 4 Given is mass in grams and unknown is mass in grams mass given (in g)  amount given (in mol)  amount unknown (in mol)  mass unknown (in g)

MUST HAVE… Correct molecular formulas Balanced chemical equation

Mole Ratios Conversion factor relating amount of moles of any two substances

Example: decomposition of aluminum oxide

Molar Mass Ratios Al 2 O 3 – g/mol Al – g/mol O 2 – g/mol

Stoichiometric Calculations: Type 1 (mol-mol) Example 1: The combustion of 2.19 mol propane (C 3 H 8 ) produces how much carbon dioxide? Example 2: 41.8 mol lithium hydroxide is combined with carbon dioxide to produce lithium carbonate and liquid water. How many moles of water are produced?

Stoichiometric Calculations: Type 2 (mass-mol) NaHCO 3 and Mg(OH) 2 are both used as antacids – which is more effective per gram? Example 3: 1.00 g NaHCO 3 reacts with hydrochloric acid to produce sodium chloride, water, and carbon dioxide Example 4: 1.00 g Mg(OH) 2 reacts with hydrochloric acid to produce magnesium chloride and water

Stoichiometric Calculations Type 3 (mol-mass) In photosynthesis, plants use energy from the sun to produce glucose C 6 H 12 O 6, and oxygen from the reaction of carbon dioxide and water. What mass, in grams, of glucose is produced when 3.00 mol of water react with carbon dioxide?

Stoichiometric Calculations Type 3 (mol-mass) What mass of carbon dioxide, in grams, is needed to react with 3.50 mol of water in the photosynthetic reaction?

Stoichiometry Calculations Type 4 (mass-mass) Tin (II) fluoride is used in some toothpastes. It is made by the reaction of tin with hydrogen fluoride according to the following equation. Sn(s) + 2HF  SnF 2 (s) + H 2 (g) How many grams of SnF2 are produced from the reaction of g of HF with Sn?