1. Stoichiometry: The math relationships between substances involved in chemical reactions. Stoichiometry allows us to make predictions How much of A do we need to make B How much B can we produce if we start from B If we have 40% yield, how much A must we use in order to get 100 g B. If we have 20 grams of reactant A and 20 g of reactant B, how much product will we make? All stoichiometry problems are solved in a similar manner once you learn the procedure, these problems will seem easy….. So…… Here we go!

2. 1. How many grams of NaAlO 2 can be obtained from 4.46 g of aluminum chloride according to the following reaction? AlCl 3 + 4 NaOH  NaAlO 2 + 3 NaCl + 2 H 2 O ? g 4.46 g gfw AlCl 3 mole AlCl 3 mole ratio mole NaAlO 2 gfw NaAlO 2 4.46 g AlCl 3 Al = 27.0 3Cl = 3(35.4) 133.2 g/mole Mole AlCl 3 133.2 g AlCl 3 1mole NaAlO 2 1 mole AlCl 3 82.0g NaAlO 2 Mole NaAlO 2 Na = 23.0 Al = 27.0 2O = 32.0 82g/mole NaAlO 2 = 2.74 g NaAlO 2

3. 2. How many grams of hydrochloric acid are required to react completely with 61.8 g of calcium hydroxide? 2 HCl + Ca(OH) 2  2 H 2 O + CaCl 2 ? g61.8 g gfw Ca(OH) 2 mole Ca(OH) 2 mole ratio mole HCl gfw HCl 61.8 g Ca(OH) 2 H = 1.0 Cl = 35.4 36.4 g/mole HCl Mole Ca(OH) 2 74.0 g Ca(OH) 2 2mole HCl 1 mole Ca(OH) 2 36.4 g HCl mole HCl Ca = 40.1 2O = 32.0 2H = 2.0 74.0g/mole Ca(OH) 2 = 60.8 g HCl

4. 1. 3.How many grams of hydrogen are produced when 4.72 g of aluminum reacts with excess sulfuric acid? 2 Al + 3 H 2 SO 4  3 H 2 + Al 2 (SO 4 ) 3 ? g 4.72 g gfw Al mole Al mole ratio mole H 2 gfw H 2 4.72 g Al Al = 27.0 g/mole mole Al 27.0 mole Al 3 mole H 2 2mole Al 2.00 g H 2 mole H 2 2 H = 2.00 g/mole = 0.524 g H 2

5. 4. The action of carbon monoxide on iron(III) oxide can be represented by the equation Fe 2 O 3 + CO  Fe + CO 2. What is the minimum mass of carbon monoxide produced if 57.5 grams of iron were produced. (Hint) Make sure the equation is balanced before beginning. Fe 2 O 3 + 3 CO  2 Fe + 3 CO 2 ? g 57.5 g gfw Fe moles Fe mole ratio moles CO gfw CO 57.5 g Fe mole Fe 55.8 g Fe 3 mole CO 2 mole Fe 28.0 g CO mole CO C = 12.0 O = 16.0 28 g/mole CO

6. 6.Claude-Louis Berthollet first prepared ethyne (acetylene) by sparking carbon electrodes in hydrogen gas. 2C + H 2  C 2 H 2 How many grams of the carbon electrode will be consumed when 59.8 g of acetylene are produced? Answer: 55.2 g C Show how we got this answer!