2. The Concept of: A little different type of yield than you had in Driver’s Education class.

3. What is Yield? u Yield is the amount of product made in a chemical reaction. u There are three types: 1. Actual yield- what you actually get in the lab when the chemicals are mixed 2. Theoretical yield- what the balanced equation tells should be made 3. Percent yield 3. Percent yield = Actual Theoretical x 100

4. Example: u 6.78 g of copper is produced when 3.92 g of Al are reacted with excess copper (II) sulfate. 2Al + 3 CuSO 4  Al 2 (SO 4 ) 3 + 3Cu u What is the actual yield? u What is the theoretical yield? u What is the percent yield? = 6.78 g Cu = 13.8 g Cu = 49.1 %

5. PERCENT YIELD EXAMPLE: Ex: N 2(g) + 3H 2(g)  2NH 3(g) When 7.5 x 10 1 g of N 2(g) reacts with hydrogen, the theoretical yield is 9.10 g. If only 1.72 g of NH 3(g) is obtained in exp, what is the % yield?

6. PERCENT YIELD EXAMPLE: u Theoretical yield: 9.10 g u Actual yield: 1.72 g Percent Yield = Actual yield x 100 % Theoretical yield Percent yield = 1.72 g x 100% 9.10 g = 18.9 % Not very close to 100% (81.1% error!!!!) Not very good results! 

7. HOMEWORK u Practice Problems page 319 #51-54

8. Details on Yield u Percent yield tells us how “efficient” a reaction is. u Percent yield can not be bigger than 100 %. u Theoretical yield will always be larger than actual yield! Why? Due to impure reactants; competing side reactions; loss of product in filtering or transferring between containers; measuring

9. References Walt Sautter