Percentage yield

Question 1

What is the theoretical yield?

Answer 1

In any chemical reaction: no atoms are gained or lost, and the total mass stays the same. This means that, for a given mass of a limiting reactant, you can make only a maximum mass of a product. This is the theoretical yield.

Question 2

What is the actual yield?

Answer 2

The actual yield is the mass of product that you really get at the end of a chemical process. This is always less than the theoretical yield.

Question 3

What are some reasons for not obtaining the theoretical yield?

Answer 3

1) Incomplete reaction - the reaction has not finished or has reached equilibrium.
2) Side reactions - competing, unwanted reactions, so by-products are also made.
3) Practical losses during the experiment - losses during purification or during transfers.