Unit 1 Section 2 Atom Economy

Atom Economy: A measure of the proportion of reactant atoms that become part of the desired product in a balanced chemical reaction.

Atom Economy in Industry:

• Try to use reactions with a high atom economy.
• So they're not spending money producing waste or by-products.
• Reactions with a low atom economy may still be used if their waste can be sold or used elsewhere (gases, salts and acids can often be useful in other reactions).

Calculating Atom Economy:

% atom economy = (mass of desired product / total mass of reactants) x 100

E.g. Ethanol can be produced by fermenting glucose: C6H12O6 >>> 2C2H5OH + 2CO2

Calculate the % atom economy for this reaction.

1. Calculate the total mass of the reactants (1 mole of glucose):

(6 x 12) + (12 x 1) + (6x16) = 180

2. Find the mass of the desired product (2 moles of ethanol):

2 x ((12 x 2) + (5 x 1) + 16 + 1) = 92

3. % atom economy = (92 / 180) x 100 = 51.1%