yields sc14a

Question 1

State what is meant by the theoretical yield of a reaction

Answer 1

the theoretical yield of a reaction is the maximum possible mass of product you’d make if all the reactants were converted into products. theoretical yield can be calculated from the balanced reaction equation

Question 2

State what is meant by the actual yield of a
reaction.

Answer 2

An actual yield is the mass of a product actually obtained from the reaction. It is always less than the theoretical yield.

Question 3

Calculate the percentage yield of a reaction.

Answer 3

percentage yield = actual yield ÷ theoretical yield

Question 4

Understand that the actual yield is always less than the theoretical yield of a reaction.

Answer 4

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

Question 5

Describe some reasons why the actual yield is less than the theoretical yield of a reaction.

Answer 5

incomplete reactions: if not all of the reactants are converted to product, the reaction is incomplete and the yield will be lower than expected

practical losses: you always lose a bit when you transfer chemicals between containers. imagine pouring a liquid into a new container - some is always left on the inside surface of the old container

unwanted reactions - if unexpected reactions happen, the yield of the intended product goes down. these can be caused by the impurities in the reactants, or sometimes by changes to the reaction conditions