4.3.3 Yield and atom economy of chemical reactions

Question 1

What is yield?

Answer 1

Your return, how much is obtained as a percentage

Question 2

Compare theoretical and experimental mass.

Answer 2

Theoretical mass is the maximum mass of a product that can be obtained.
Experimental mass is what you actually get in practice by doing the experiment

Question 3

Atom Economy =

Answer 3

(molar mass of useful products / (molar mas of all products or molar mass of all reactants)) * 100

Question 4

Percentage Yield =

Answer 4

(experimental mass of material produced / theoretical max mass which could be produced) * 100

Question 5

What are the reasons few chemical reactions may have a yield of 100%?

Answer 5

• The raw materials may not be pure < not ideal answer
• Some of the products may be left behind on the apparatus < preferred answer
• The reaction may not have completely finished < good answer
• Some reactants may give some unexpected products / side reactions take place < valid answer
• Some reactions are reversible e.g. the Haber Process < good answer