STOICHIOMETRY A recipe for chemistry Step 1 Stoichiometry

STOICHIOMETRY A recipe for chemistry!

Step 1 § Stoichiometry begins with a balanced chemical equation. § This means that formulas must be written correctly and you may even have to predict the products!!

Step 2 § Use ratios from the BCE to determine the amount of reactants needed or the amount of products formed from the given substance and quantity.

Step 3 § If quantity is given in moles, go directly to the mole ratio from the BCE. § If given grams, convert to moles before using the mole ratio from the BCE.

Step 4 § Check to make sure answer is in the correct form (unit) that was asked for in the problem.

Example 1: Mole to Mole § BCE 2 H 2 + O 2 2 H 2 O § There are 6 possible mole ratios. § (1 < than # of “things” times the # of “things” (reactants and products)) § 2 H 2: 1 O 2 2 H 2: 2 H 2 O § 1 O 2: 2 H 2 O § 2 H 2 O: 1 O 2

2 H 2 + O 2 2 H 2 O § How many moles of water will be produced from 6. 5 moles of oxygen? § 6. 5 mol O 2 § 2 mol H 2 O = 13 mol H 2 O 1 mol O 2

2 H 2 + O 2 2 H 2 O § How many moles of hydrogen are needed to completely react with 4. 23 mol of oxygen? § How many moles of water can be produced? § 4. 23 mol O 2 § 2 mol H 2 1 mol O 2 § 4. 23 mol O 2 § 2 mol H 2 O 1 mol O 2 = =

Example 2: mass to mole § 18. 2 grams of hydrogen react completely. How many moles of water can be produced? § 2 H 2 + O 2 2 H 2 O § 18. 2 g H 2 1 mol H 2 2 mol H 2 O = 9. 01 mol H 2 O 2. 02 g H 2 2 mol H 2 §

§ 2 Na(s) + Cl 2(g) 2 Na. Cl(s) How many moles of sodium are needed to produce 2. 4 grams of sodium chloride? 2. 4 g. Na. Cl 1 mol Na. Cl 2 mol Na = 58. 44 g Na. Cl 2 mol Na. Cl

2 Na(s) + Cl 2(g) 2 Na. Cl(s) § How many moles of chlorine are needed to produce 2. 4 grams of sodium chloride? § 2. 4 g Na. Cl 1 mol Cl 2 __ = § 58. 44 g Na. Cl 2 mol Na. Cl

Answers to homework mole/mole and mass/mole § § § § Mole to Mole 1. 6. 0 mole H 2 2. 4. 0 mole NH 3 9. 0 mol O 2 3. 3. 5 mol H 2 4. 2. 84 mol Zn. Cl 2 5. 18 mol O 2 6. 11 mol CO 2 § § § § Mass to Mole 1. 721 g C 6 H 12 O 6 2. 432 g H 2 O 3. 321 g Na. Cl 4. 213 g Cl 2 5. 419 g HCl 6. 9. 09 g H 2

Example 3: mass to mass § 4 NH 3 + 5 O 2 4 NO + 6 H 2 O How many grams of water can be produced from 15. 6 grams of ammonia? 15. 6 g NH 3 1 mol NH 3 6 mol H 2 O 17. 04 g NH 3 4 mol NH 3 = 18. 02 g H 2 O 1 mol H 2 O

4 NH 3 + 5 O 2 4 NO + 6 H 2 O § How many grams of oxygen are needed to produce 21. 7 grams of NO? 21. 7 g NO 1 mol NO 5 mol O 2 30. 01 g NO 4 mol NO = 32. 00 g O 2 1 mol O 2

Mass to Mass & Mixed Stoichiometry § § § § Mass to mass 1. 15. 2 g KCl 2. 9. 79 g O 2 3. 10. 8 g H 2 4. 60. 8 g NH 3 5. 4. 2 g Ag. Cl 6. 3. 1 g Ba. Cl 2 § § § § Mixed 1. 1. 78 mol NH 3 2. 36. 4 g H 2 3. 40. 8 g Na. OH 4. 8. 1 g H 2 O 5. 2. 24 g Cu 6. 780 g Ag. NO 3