How to Calculate Theoretical Yield of a Chemical Reaction?

The theoretical yield of a chemical reaction is the product calculated by assuming that the reaction goes to completion. In reality, all of the reactants are not consumed and all of the products are not recovered. Thus a certain percentage of the products are recovered. This is called the percent yield. Theoretical yield is the amount of product we would recover if 100% of the reactant reacted. The maximum amount of product that can be produced from given amounts of reactant.

The term percent yield is used to indicate how much of a desired product is obtained from a reaction.

Theoretical yield of product = actual yield of product/Percent yield x 100%

Let’s solve a problem based on theoretical yield.

Problem: Consider the following reaction.
C₂H₅OH + CH₃COOH --> CH₃COOC₂H₅ + H₂O

If the yield of ethyl ethanoate obtained when 20.00g of ethanol is reacted with excess ethanoic acid is 30.27g. Calculate the theoretical yield.

Solution:

Molar mass of C₂H₅OH = 46.08 g/mol

Number of moles of C₂H₅OH = 20.00/46.08 = 0.4340 mol

The molar mass of CH₃COOC₂H₅ = 88.12 g/mol

The mass of ethyl ethanoate CH₃COOC₂H₅ = 0.4340 x 88.12 = 38.24g.

Therefore the theoretical yield is 38.24g.