1. Percent Yield in Reactions Welcome to The Real World

2. Ideal Conditions All reactants actually react. No outside influences exist. People don’t screw things up. There are no acts of nature. Dream on.

3. For whatever reason Nothing happens in a vacuum No chemical reaction is perfect Usually a fraction of the expected yield is produced Theoretical yield: What the calculation says we should get Actual yield: What is really produced. Percentage Yield = Actual yield/theoretical yield x 100

4. Example 1 A student conducts a single displacement reaction that produces 2.755 grams of copper. Mathematically he determines that 3.150 grams of copper should have been produced. Calculate the student's percentage yield. Solve: actual amount of product: 2.755 g expected amount of product: 3.150 g

5. Example 1 continued actual amount of product percentage yield = ------------------------------------------- x 100 expected amount of product 2.755g percentage yield = --------------- x 100 3.150g percentage yield = 87.4603174 % percentage yield = 87.46 %

6. Example 2 Solid sodium nitrate decomposes to form solid sodium nitrite and oxygen gas 2NaNO 3  2NaNO 2 + O 2 If the percentage yield is 80.4%, how much sodium nitrite will be produced from 955g of NaNO 3 ?

7. Solution Divide by molar mass of NaNO 3 Multiply by the coefficient ratio Multiply by molar mass of NaNO 2 Multiply by percentage yield \\admin2000\facultysettings$\dsandberg\do cuments\Example problem 2 percent yield.doc \\admin2000\facultysettings$\dsandberg\do cuments\Example problem 2 percent yield.doc

8. Assignment Percentage Yield Problem Set