# 13_ Percent Yield

Document Sample

```					PERCENTAGE YIELD
SECTION 7.3
THEORETICAL YIELD

• Predicted yield you obtain
by using the equation
• The amt you “should” obtain
using stoichiometry
ACTUAL YIELD
• Amount of product produced in an
experiment
• Usually actual yield will be lower
than theoretical yield
UH OH!

• WHY???
– Human error
– Experimental error
Some experimental errors…
• Procedure not followed correctly
• Equipment: broken/not clean
• Reaction not complete
• Other “side reactions” happen at same
time
• Loss of product
PERCENT YIELD
• Tells you how CLOSE your actual yield is
to the theoretical yield (what you should

Percent Yield = Actual yield x 100 %
Theoretical yield

• the closer you are to 100%, the better
the yield
PERCENT YIELD EXAMPLE 1:
Ex: N2(g) + 3H2(g)    2NH3(g)

When 7.5 x 101 g of N2(g) reacts with
hydrogen, the theoretical yield is 9.10 g.
If only 1.72 g of NH3(g) is obtained in exp,
what is the % yield?
PERCENT YIELD EXAMPLE:
• Theoretical yield: 9.10 g
• 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! 
PERCENT YIELD EXAMPLE 2:
• Ex: N2(g) + 3H2(g)   2NH3(g)

The actual yield of NH3 is 2.50g, when
1.5 x 101 g of N2 reacts. What is the
percent yield?

Hint: Calculate Theoretical yield first! 
HOMEWORK
• Pg 262 # 31, 32
• Pg 264 # 34, 36

```
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
 views: 4 posted: 2/18/2012 language: English pages: 9