Chapter 9B Notes Stoichiometry West Valley High School General Chemistry Mr. Mata

Grams -> grams Calculation Steps: 1. Balance the chemical equation. 2. Write grams of given reactant/product. 3. Use molar mass to find mole/gram ratio. 4. Multiply by the mole/gram ratio: given g A x mol A x mol B x g B = ___ g B g A mol A mol B

Route to Calculating Mass Relationships Insert figure 11.1

Example Problem #1 N2 + 3 H2 2NH3 How many grams of NH3 will be produced if you start with 50 grams of N2? Grams A moles A moles B grams B Grams N2 moles N2 moles NH3 grams NH3 Step 1: grams N2 mol N2 50 grams N2 x 1 mol N2 = 1.8 mol N2 28 grams N2

Example Problem #1 N2 + 3 H2 2NH3 How many grams of NH3 will be produced if you start with 50 grams of N2? Grams N2 moles N2 moles NH3 grams NH3 Step 2: mol N2 mol NH3 1.8 mol N2 x 2 mol NH3 = 3.6 mol NH3 1 mol N2

Example Problem #1 N2 + 3 H2 2NH3 How many grams of NH3 will be produced if you start with 50 grams of N2? grams N2 moles N2 moles NH3 grams NH3 Step 3: mol NH3 grams NH3 3.6 mol NH3 x 17 gram NH3 = 61.2 g NH3 1 mol NH3

Example Problem #2 N2 + 3 H2 2NH3 How many grams of NH3 will be produced if you start with 12 grams of H2? grams H2 moles H2 moles NH3 grams NH3 Step 1: grams H2 mol H2 12 grams H2 x 1 mol H2 = 6 mol H2 2 grams H2

Example Problem #2 N2 + 3 H2 2NH3 How many grams of NH3 will be produced if you start with 12 grams of H2? grams H2 moles H2 moles NH3 grams NH3 Step 2: mol H2 mol NH3 6 mol H2 x 2 mol NH3 = 4 mol NH3 3 mol H2

Example Problem #2 N2 + 3 H2 2NH3 How many grams of NH3 will be produced if you start with 12 grams of H2? grams H2 moles H2 moles NH3 grams NH3 Step 3: mol NH3 grams NH3 4 mol NH3 x 17 grams NH3 = 68 grams NH3 1 mol NH3

Example Problem #3 __ KNO3 + __ Fe2O3 -> __ K2O + __ Fe(NO3)3 How many grams of K2O will be produced if you start with 80 grams of Fe2O3? grams Fe2O3 moles Fe2O3 moles K2O g K2O Step 1: grams Fe2O3 mol Fe2O3 80 grams Fe2O3 x 1 mol Fe2O3 = 0.5 mol Fe2O3 160 grams Fe2O3

Example Problem #3 Step 2: mol Fe2O3 mol K2O 6 KNO3 + Fe2O3 -> 3 K2O + 2 Fe(NO3)3 How many grams of K2O will be produced if you start with 80 grams of Fe2O3? g Fe2O3 moles Fe2O3 moles K2O g K2O Step 2: mol Fe2O3 mol K2O 0.5 mol Fe2O3 x 3 mol K2O = 1.5 mol K2O 1 mol Fe2O3

Example Problem #3 Step 3: mol K2O grams K2O 6 KNO3 + Fe2O3 -> 3 K2O + 2 Fe(NO3)3 How many grams of K2O will be produced if you start with 80 grams of Fe2O3? g Fe2O3 moles Fe2O3 moles K2O K2O Step 3: mol K2O grams K2O 1.5 mol K2O x 94 grams K2O = 141 g K2O 1 mol K2O

Chapter 9B SUTW Prompt Describe the difference between solving a mole:mole and a mass:mass stoichiometry problem. Complete a 8 - 10 sentence paragraph using the SUTW paragraph format. Hilight using green, yellow, and pink. Due Date: Monday, November 27th, 2017(start of class).