1. Ideal Stoichiometric calculations Chapter 9.2

2. Objectives: Calculate the amount in moles of a reactant or product from the amount in moles of a different reactant or product. Calculate the mass of a reactant or product from the amount in moles of a different reactant or product. Calculate the amount in moles of a reactant or product from the mass of a different reactant or product. Calculate the mass of a reactant or product from the mass of a different reactant or product.

4. Reactants are completely converted to products

5. Theoretical, and hardly ever met in laboratory setting

7. Sample Problem 1 In a spacecraft, the carbon dioxide, exhaled by astronauts can be removed by its reaction with lithium hydroxide, LiOH, according to the following chemical equation. CO2(g) + 2 LiOH(s) Li2CO3(s) + H2O(l) How many moles of lithium hydroxide are required to react with 20 mol of CO2, the average amount exhaled by a person each day. CO2(g) + 2 LiOH(s) Li2CO3(s) + H2O(l) mass 2 moles 20 mol 40 mol 1

8. Conversions: Moles to Mass Problem type 2: mol A mol B mass B Conversion factor is mole ratio and molar mass Now find the mass of H2O 2 H2 + O2 2 H2O 72.1 g mass x 18.02 g/mol 2 mol 2.oo mol 4.00 mol moles 1 mol Extra steps: 1. Map out till you get what you are looking for. 2. Convert using molar mass.

9. Sample Problem 2 In photosynthesis, plants use energy from the sun to produce glucose, C6H12O6, 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? CO2(g) + H2O(l) C6H12O6(s) + O2(g) 6 6 6 mass 90.1 g x 180.18 g/mol 1 3.00 mol 0.500 mol moles 6 C 6 x 12.01 = 72.06 g H 12 x 1.01 = 12.12 g O 6 x 16.00 = 96.00 g 180.18 g/mol

10. Sample Problem 3 What mass of carbon dioxide, in grams, is needed to react with 3.00 mol of H2O in the photosynthetic reaction described in the last sample problem? CO2(g) + H2O(l) C6H12O6(s) + O2(g) 6 6 6 mass 132 g 90.1 g x 180.18 g/mol x 44.01 g/mol 1 6 3.00 mol 0.500 mol moles 3.00 mol 6 6

11. Conversions of Mass to Amounts in Moles Problem type 3: mass A mol A mol B Conversion factor is mole ratio and molar mass Sample Problem 4 The first step in the industrial manufacture of nitric acid is the catalytic oxidation of ammonia. The reaction is run using 824 g of NH3 and excess oxygen. How many moles of NO and H2O are formed? NH3(g) + O2 (g) NO(g) + H2O(g) 4 4 6 5 mass 824 g ÷ 17.04 4 6 48.4 mol 72.6 mol moles 48.4 mol 4 4

12. Mass – Mass Calculations Problem type 4: mass A mol A mol B mass B Conversion factor is mole ratio and molar mass Sample Problem 5 Tin(II) fluoride,SnF2, is used in some toothpastes. It is made by the reaction of tin with hydrogen fluoride. How many grams of SnF2 are produced from the reaction of 30.00 g of HF with Sn? Sn(s) + HF(g) SnF2(s) + H2 (g) 2 30.00 g 117.5 g mass ÷ 20.01 g/mol x 156.71 g/mol 1 1.500 mol 0.7500 mol moles 2