Yield of a reaction:
The quantity of product produced in a reaction is called yield of the reaction.
Types of Yield of a reaction
yield of the reaction is of three types.
(i) Theoretical Yield:
The quantity of product as calculated by stoichiometric calculations or calculations based on balanced equation is called theoretical yield.
(ii) Actual Yield:
The quantity of product that is practically obtained after the completion of reaction is called actual yield.
- The actual yield is always less than theoretical yield due to following reasons.
- Mechanical losses:
- Mechanical losses may occur at different stages e.g. while handling of sample, during separation of product, during purification of product etc.
- Side reactions: Some time due to side reactions, some of the reactants or product change to another substance and therefore amount of actual product will be less.
- Reversibility of reaction:
- Due to reverse reaction some of the product changes back to reactants.
- Non-activated molecules:
- All the molecules of reactants are not activated. Non-activated molecules (i.e. molecules possessing energy less than activation energy) will not react.
- every sample has impurities in it. Even highly pure substance has little bit impurities. So actual yield will be less.
- Reaction conditions: If conditions are not favorable then actual yield will be low.
So it is worth to calculate percentage yield.
(iii) Percentage Yield:
Percentage Yield = Actual yield x 100