1. CHM 108 SUROVIEC FALL 2014 Chemical Quantities

2. I. Reaction Stoichiometry Given the recipe for 16 pancakes:  2 cups flour  2 teaspoons baking powder  2 eggs  1 cup milk 2

3. I. Reaction Stoichiometry For molecule we have the balanced chemical equation 3

4. A. Mass to Mass Conversions The question when synthesizing a compound is how much will this reaction make Using the balanced chemical equation we can answer that. CaF 2 + H 2 SO 4  CaSO 4 + 2HF 4

5. II. Limiting Reagents When carrying out a reaction it is often the case that the reactants are not in exact stoichiometric amounts One will always be used up first: limiting reagent One will always be in excess: excess reagent C 6 H 12 O 6 (s) + 6O 2 (g)  6CO 2 (g) + 6H 2 O (l) 5

6. A. Limiting Reactant, Theoretical Yield and Percent Yield 6 In the lab we often want to know how much product can be made (theoretical yield) vs. how much we actually made (percent yield) 2Ca(s) + O 2 (g)  2CaO (s) If you start with 43.8g of Ca(s) and 32.5g of O 2 what is the limiting reagent and theoretical yield?

7. Example 7 Now lets say you did this same reaction (previous slide) and produced 57.42 grams of CaO. What was the percent yield?

8. IV. Solution Concentration and Stoichiometry 8 Working with aqueous solutions is very common in the lab so we need to look at how they are prepared and used. Solution Solvent Solute

9. A. Solution Concentration 9 Molarity is defined as moles/Liter If 15.5g of Na 2 CO 3 is dissolved into water to make 1.50L, what is the molarity?

10. B. Using molarity 10 How many grams of glucose, C 6 H 12 O 6, are needed to make a 2.00L solution of 0.750M?

11. C. Dilution 11 HCl comes as a 12M solution, but the experiment calls for 500 mL of 0.100M. How will you make this?

12. D. Solution Stoichiometry 12 What volume (in mL) of a 0.150M HNO 3 solution is required to completely react with 37.7 mL of a 0.110 M Na 2 CO 3 solution according to the equation below? Na 2 CO 3 (aq) + 2HNO 3 (aq)  2NaNO 3 (aq) + CO 2 (g) + H 2 O (l)