determined by subtraction:
(or 11.3g when considering significant figures)
PERCENT YIELD OF A PRODUCT
In most stoichiometric problems, we assume that the results are exactly what we
would theoretically expect. In reality, the resulting theoretical yield is rarely the
actual yield. Why the actual yield of a reaction may be less than the theoretical
yield occurs for many reasons. Some of the product is often lost during the
purification or collection process.
Chemists are usually interested in the efficiency of a reaction. The efficiency
is expressed by comparing the actual and the theoretical yields.
The percent yield is the ratio of the actual yield to the theoretical yield,
multiplied by 100%.
Example
Aluminum is commonly produced by the smelting of aluminum oxide into
aluminum metal by the reaction below:
2Al 2 O 3 (dissolved) + 3C(s) → 4Al(ℓ) + 3CO 2 (g)
If 3.89 kg of aluminum oxide is smelted and the actual yield of Al is 1.95 kg,
what is the percent yield associated with the process?
The theoretical yield of aluminum from that amount of aluminum oxide can
be found using dimensional analysis:
The percent yield can then be found:
CHAPTER SUMMARY
The following terms summarize all the concepts and ideas that were introduced in
this chapter. You should be able to explain their meaning and how you would use
them in chemistry. They appear in boldface type in this chapter to draw your