Percentage Yield

The amount of a product obtained is known as the yield.

Percentage yield compares the actual yield with the predicted yield.

Percentage yield = actual yield (g)/predicted yield(g) x100

100% means you get all the product you expected.

0% means no reactants where converted into a product.

Even though no atoms are gained or lost in a chemical reaction, it is not always possible to obtain the calculated amount of a product because:

• The reaction may not go to completion because it it reversible 
• Some of the product may be lost when it is separated form the reaction mixture
• Some of the reactants may react in ways different from the expected reaction. 

A reversible reaction is one where the products of the reaction can themselves react to produce the original reactants.

A + B = C + D

Example: 

Ammonium Chloride = Ammonia + Hydrogen Chloride

Product Yield is Important:

• For sustainable development - making sure we don't use resources faster than they can be renewed, enough for future generations.
• For commercial use

Using as little energy as possible to create the highest product yield possible or recyclable reactants means that resources and money  are saved.