# Percent Yield in Reactions by xiagong0815

VIEWS: 3 PAGES: 8

• pg 1
```									Percent Yield in Reactions

Welcome to The Real World
Ideal Conditions
   All reactants actually react.
   No outside influences exist.
   People don’t screw things up.
   There are no acts of nature.
   Dream on.
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
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
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 %
Example 2
   Solid sodium nitrate decomposes to form
solid sodium nitrite and oxygen gas
2NaNO3  2NaNO2 + O2

If the percentage yield is 80.4%, how much
sodium nitrite will be produced from 955g
of NaNO3?
Solution
   Divide by molar mass of NaNO3
   Multiply by the coefficient ratio
   Multiply by molar mass of NaNO2
   Multiply by percentage yield