SC14b Atom Economy

Question 1

What is atom economy?

Answer 1

The percentage by mass of reactants that are converted into useful products.

Question 2

Atom economy =

Answer 2

Mr of the useful product /relative formula masses of reactants x 100%

Question 3

What is a example of 100% atom economy?

Answer 3

Haber process.

Question 4

Calculate the atom economy for making iron in the following reaction
FE203 + 3CO → 2Fe + 3CO2

Answer 4

FE203 + 3CO → 2Fe + 3CO2
Mr 160 3x28 2x56
atom economy of iron = 112/244 x 100
= 45.9%

Question 5

What does high percentage yield but low atomic economy mean?

Answer 5

Waste products are produced

Question 6

Does percentage yield give indication of quantity of waste?

Answer 6

No.

Question 7

What do chemists choose to? when picking reaction pathways?

Answer 7

Atom economy
Energy consumption
Reaction rate
Raw materials eg cost, storage, availability
Conditions for high yield

Question 8

Calculate the atomic economy for making ammonia from ammonium sulphate in the following reaction. )NH4)2SO4 + 2NaOH → 2NH3 + NA2SO4 + 2H2O.

Answer 8

Mr NH3 = 17
(NH4)2SO4 = 132.13952
NaOH = 40
atom economy = 34/212.13952 x 100 = 16%