# Atom economy

• Created by: Mhind27
• Created on: 09-10-18 10:27

## Atom Economy

A lot of reactions make more than one product. Some of them will be useful, but others will be waste. The Atom economy (or atom utilisation) of a reaction tells you how much of the mass of the reactant is wasted when manufacturing a chemical and how much ends up as desired products. The equation is:

Atom Economy= Relative mass of desired products         X100                                                                         Relative formula mass of all reactants

100%  Atom economy means that all the atoms in the reactants have been turned into desired products. The higher the atom economy the 'greener' the process.

Calculate the atom economy of this reaction: CH4(g) + H20(g) -> CO(g) + 3H2 (g)

Identify the desired product - that's hyrdogengas. Work out the of all the reactants. Work out the total of all desired product: Mr(CH4) = 12.0 + (4 X 1.0) = 16.0    Mr(H20)= (2 X 1.0) +16.0 = 18.0   16.0 + 18.0 = 34.0   3 X Mr (H2) = 3 X (2 X 1.0) = 6.0     6.0 X100                                                                                                                               34.0       = 17.6%

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