Yield of Reaction

 

Yield

The amount of the product obtained as a result of the chemical reaction is called yield.

Types of Yield

Theoretical Yield/ Stoichiometric yield/ calculated yield/ expected yield

The amount of the products calculated from the balanced chemical equation by a given amount of reactant is known as theoretical yield or stoichiometric yield or calculated yield or expected yield.

It is the maximum amount of the product that can be produced theoretically and stoichiometrically by known amount of a reactant according to balanced chemical equation.

Theoretical yield of a reaction is always greater than the actual yield of the same reaction.

Actual Yield/ Experimental Yield

The amount of the products actually obtained from a given amount of the reactant in a chemical reaction experimentally is called the actual yield or experimental yield of that reaction.

The actual yield of a reaction is always less than the theoretical yield

Percentage Yield

The efficiency of a chemical reaction can be checked by calculating its percentage yield which is expressed by comparing the actual yield and theoretical yields

Competing side reactions may also occur decreasing practical yield.

Reason of Less Actual Yield

The actual yield of a reaction is always less than the theoretical yield because of following reasons:

1.         The reaction may not go to completion and may reduce the yield of the product.

2.         Side reactions may produce by-products (i.e. some of the reactants might take part in a competing side reaction and reduced the amount of the desired product.

3.         Reversibility of reactions leads to less products.

4.         Materials may be lost in handling.

5.         Mechanical loss takes place due to filtration, distillation and separation by separating funnel, washing and crystallization etc.

6.         A practically inexperienced worker has many shortcomings and cannot get the expected yield.

Difference between Theoretical yield and actual yield