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It's particularly important in industrial chemical reactions to try to maximise the percentage yield of the desired product(s).

Help in using percentages is provided in the Maths skills course; further information can be found by subscribing to the Quantitative chemistry course.

The percentage yield in an equilibrium process can be affected by the operating conditions. Think about the generalised equilibrium system:

A(g) + 2B(g) _∏ C(g)  ΔH –ve

How will temperature affect the percentage yield of product C?

A low temperature will increase the yield of product C.

How will the pressure affect the yield of product C?

A high pressure will increase the yield of product C.

How will the presence of a catalyst affect the percentage yield of product C?

A catalyst doesn't affect the percentage yield of a reaction. It will, however, affect the rate at which equilibrium is established.