1. Chemistry Chapter 9 - Stoichiometry South Lake High School Ms. Sanders

2. The Mole  Mole Ratio  From balanced equation; coefficients  Used to convert from moles of one substance to moles of another substance  Example: 2H ₂ + O₂ 2H₂O

3. Conversions  Mole to Mole Conversions  Given x unknown = unknown  Mole A x Mole B = Mole B Mole A mole ratio

4. Conversions  Mole to Mole Conversions  Practice page 306 1)3H ₂ + N₂ 2NH₃ How many moles of ammonia are produced from 6 moles of hydrogen gas?

5. Conversions  Moles to Grams Conversion molar mass  Mole A x Mole B x g B = g B Mole A Mole B mole ratio

6. Conversions  Mole to Grams Conversion  Practice page 308 1)2Mg + O ₂ 2MgO What mass of magnesium oxide is produced from 2 moles of magnesium?

7. Conversions  Grams to Moles Conversions mole ratio  g A x Mole A x Mole B = Mole B g A Mole A molar mass

8. Conversions  Grams to Moles Conversion  Practice page 309 1)2HgO 2Hg + O ₂ How many moles of mercury oxide are needed to produce 125 g of oxygen?

9. Conversions  Grams to Grams Conversion  Gram A to Mole A to Mole B to Gram B molar mass B  g A x Mole A x Mole B x g B = g B g A Mole A Mole B molar mass A mole ratio

10. Conversions  Grams to Grams Conversion  Practice page 311 1)NH ₄NO₃ N₂O + 2H₂O How many grams of NH₄NO₃ are needed to produce 33.0 g of N₂O?

11. Limiting Reagents  The first to be used up in a chemical reactions  Controls the amount of product produced  When the limiting reagent is used up, the reaction stops

12. Limiting Reagents  How to find the limiting reagent:  1) Solve for the moles of the first product – start with the moles of each reactant (do it twice)  2) Whichever reactant produces the least amount of product, is the limiting reagent

13. Limiting Reagents  Practice page 313  1) N ₂H₄ + 2H₂O₂ N₂ + 4H₂O  a) Which is the limiting reagent when 0.75 moles of N₂O₄ is mixed with 0.5 moles of H₂O₂?

14. Limiting Reagents  Practice page 313  1) N ₂H₄ + 2H₂O₂ N₂ + 4H₂O  b) How much excess?

15. Limiting Reagents  Practice page 313  1) N ₂H₄ + 2H₂O₂ N₂ + 4H₂O  c) How much of each product is formed in moles?

16. Percent Yield  % yield = (actual yield/theoretical yield) x 100  Actual yield – given to you in the problem; the amount of product  Theoretical yield – have to calculate using stoichiometry g reactant to g product what we should have produced

17. Percent Yield  Practice page 318  1) CO + 2H ₂ CH₃OH If 75 g of CO reacts to produce 68.4 g of CH₃OH, what is the % yield of CH₃OH? Actual yield = Theoretic yield =