1. Objectives SWBAT define stoichiometry. SWBAT write a mole ratio relating two substances in a chemical reaction. SWBAT calculate the mass of a reactant or product from the mass of a different reactant or product.

2. Stoichiometry

3. What is Stoichiometry? “To measure elements” The study of the quantitative relationship between the amounts of reactants and products in a chemical reaction. A balanced chemical equation can be interpreted in terms of particles, mass, and moles.

4. To make a bike?

5. iron + oxygen  iron (III) oxide What is the balanced chemical equation? What does this tell us?

6. Iron + Oxygen  Iron (III) Oxide 4 Fe + 3 O 2  2Fe 2 O 3 4 atoms Fe + 3 molecules O 2  2 formula units Fe 2 O 3 4 moles Fe + 3 moles O 2  2 moles Fe 2 O 3 55.85g/mol × 4 = 223.40 g/mol + 32.00g/mol × 3 = 96.00g/mol  159.70g/mol × 2 = 319.40g/mol 223.40g/mol + 96.00g/mol = 319.40g/mol  319.40g/mol

7. Mole Ratios Solving any reaction stoichiometry problem involves the use of a mole ratio A mole ratio is a conversion factor that relates the amounts in moles of any two substances involved in a chemical reaction This information is obtained directly from the coefficients in a balanced chemical equation

8. Mole Ratios – Examples Consider the following equation: 2 H 2 + O 2 → 2 H 2 O sample mole ratios: –2 mol H 2 = 2 mol H 2 O –1 mol O 2 = 2 mol H 2 O –2 mol H 2 = 1 mol O 2

9. Sample Problem #1 Potassium and water react to form potassium hydroxide and hydrogen gas. How many moles of hydrogen are produced when 0.04 moles of potassium are used?

10. Answer 0.02 mol H 2

11. Sample Problem #2 Ammonium nitrate, an important fertilizer, produces dinitrogen monoxide and water when it decomposes. Determine the mass of the water produced from the decomposition of 25.0 g of ammonium nitrate.

12. Answer 11.2 g H 2 O

13. Answer 2.0 x 10 24 formula units of NaCl

14. Announcement! Please remove your wonderful STEM posters by next Wednesday.

15. Agenda Practice Problems Stoichiometry Worksheets

16. Homework Stoichiometry Mole to Mole Probs Stoichiometry Mass to Mass Probs Stoichiometry Volume to Volume Probs

17. Drill 3/6/14 List the number of conversion factors and type for mole-to-mole AND mass-to-mass conversion stoichiometry problems.

18. Drill 3/6/14 Conversion factors/type for mole-to-mole AND mass-to-mass conversion problems. Mole-to-mole – 1 conversion factor = mole ratio (use coefficients of “given” and “TBD” Mass-to-mass – 3 conversion factors = 1.Formula mass 2.Mole ratio 3.Formula mass

19. Homework Due – questions?? 11-2 Practice Probs WS – front side only Stoichiometry Practice #3

20. Practice Problem How many grams of water are produced when 7.00 grams of oxygen (O 2 ) react with an excess of hydrogen according to the reaction shown below? 2 H 2 + O 2 → 2 H 2 O

21. Answer 7.89 g water

22. Practice Problems Laughing gas (N 2 O) is sometimes used as anesthetic in dentistry. It is produced when ammonium nitrate is decomposed according to the following reaction: NH 4 NO 3 (s) → N 2 O (g) + 2 H 2 O (l) How many moles of NH 4 NO 3 are required to produce 33.0 g N 2 O?

23. Answer 0.750 mol NH 4 NO 3

24. Practice Problem Acetylene gas (C 2 H 2 ) is produced as a result of the following reaction: CaC 2 + 2 H 2 O → C 2 H 2 + Ca(OH) 2 If 32.0 g of CaC 2 are consumed in this reaction, how many grams of water are needed?

25. Answer 18.0 g water

26. Practice Problem Milk of magnesia, a suspension of Mg(OH) 2 in water, reacts with stomach acid, HCl, in a neutralization reaction: Mg(OH) 2 + 2 HCl → 2 H 2 O + MgCl 2 How many formula units of MgCl 2 will be produced if 3.00 g of Mg(OH) 2 reacts?

27. Drill #132/27 & 28/13 For the balanced equation shown below, how many moles of H 2 can be produced by 0.6351 moles of Al? mole to mole conversion 2 Al + 6 HCl → 2 AlCl 3 + 3 H 2

28. Answer 0.9527 mol H 2

29. Drill #143/1 & 3/4/13 Complete Empirical and Molecular Formula Drill

30. Objectives SWBAT define stoichiometry. SWBAT write a mole ratio relating two substances in a chemical reaction. SWBAT calculate the mass of a reactant or product from the mass of a different reactant or product.

31. Answer 3.10 x 10 22 formula units MgCl 2

32. Drill #2/26/14 Nitrogen and hydrogen react to form ammonia. How many grams of hydrogen are needed to react with 50.0 g of nitrogen in this reaction? Mass to mass conversion

33. Answer 10.7 g H 2