Atom Economy
- Along with the percentage yield, atom economy is used to analyse the efficiency of reactions
- Most reactions produce more than one product and very often some of them are not useful
- Atom economy studies the amount of reactants that get turned into useful products
- It illustrates what percentage of the mass of reactants become useful products
- It is used extensively in the analysis of systems and procedures in industries, in an effort to obtain sustainable development
- It is also a very important analysis for economic reasons as companies prefer to use processes with higher atom economies
- The higher the atom economy of a process then the more sustainable that process is
- The equation for calculating atom economy is:
Worked example
Hydrogen gas is obtained from methane in a process called steam-methane reforming. The reaction is as follows:
CH4 (g) + H2O (g) → CO (g) + 3H2 (g)
Calculate the atom economy of this reaction, assuming hydrogen is the only desired product.
Answer:
Exam Tip
Unwanted byproducts can sometimes be put to use so although a low atom economy is a sign that a process is not green (sustainable) it doesn’t necessarily imply that the process is not economically viable.
