Atom Economy Calculator
Atom economy of a reaction, the fraction lost to by-products, the reaction mass efficiency and the E factor.
Results
What this tool does
This is the green chemistry measure: an addition reaction where everything ends up in the product reaches one hundred percent, while a substitution that throws away a leaving group can fall below forty. The E factor turns it round and says how many kilograms of waste accompany each kilogram of product.
Formula
atom economy = molar mass of the wanted product ÷ Σ molar masses of the reactants × 100
Variables
| Symbol | Meaning | Unit |
|---|---|---|
mp | Molar mass of the product | g/mol |
mr | Molar mass of all reagents | g/mol |
yl | Percent yield | % |
AE | Atom economy | % |
WS | Percentage | % |
RM | Reaction mass efficiency | % |
EF | E factor (waste per product) | — |
Worked example
- Molar mass of the product180.16 g/mol
- Molar mass of all reagents260.2 g/mol
- Percent yield80 %
- Atom economy69.2390 %
- Percentage30.7610 %
- Reaction mass efficiency55.3912 %
- E factor (waste per product)0.44427
Limitations
- For work that must comply with a standard or be signed off, check the result against the applicable code and have it reviewed by a qualified engineer.
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
Frequently asked questions
How is this different from percent yield?
Yield asks how much of what could have formed actually did. Atom economy asks a harder question: of all the atoms you put in, how many ended up in the product you wanted rather than in something you now have to dispose of. A reaction can have a perfect hundred percent yield and a dismal atom economy, and it is the second number that decides how much waste leaves the plant.