Atom economy or percentage atom economy is simply a measure of how ‘green’ a chemical process is – it essentially calculates the amount of atoms ‘wasted’ in a reaction because these atoms don’t end up in the desired product. Obviously the higher the atom economy of a reaction, the better, and reactions that don’t produce any by-products will have an atom economy of 100%.
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Practice questions
Calculate the atom economy of these reactions:
1. Production of hydrogen CH4 + H2O ——-> 3H2 + CO
2. Extraction of copper 2CuCO3 + C ——-> 2Cu + 3CO2
Answers:
1. 17.6%
2. 49.0%