Video: Atom Economy | Formula & Examples

What is Atom Economy

Atom economy is referred to as atom efficiency, and it can be defined as how well a chemical reaction converts reactants into the products that are desired. One American chemist, Barry M. Trost, introduced this term to express the importance of reducing chemical waste during chemical production. Thus, atom economy becomes a great principle for green chemistry aimed at cleaner chemical manufacture.

Why Atom Economy Is Important

Atom economy becomes one of the most important features of green chemistry because it limits chemical waste. It makes the whole industrial process more sustainable. The bigger the atom economy value is, the bigger the number of reactants that were made into useful products as opposed to potential environmental hazard by-products. Industries maximize the atom economy to minimize the consumption of resources, waste disposal costs, and pollution.

Calculating Percentage Atom Economy

The calculation of the percentage atom economy is as given below:

{eq}\text{Atom Economy} = \left( \frac{\text{Molar Mass of Desired Product}}{\text{Total Molar Mass of Reactants}} \right) \times 100 {/eq}

The higher the atom economy, the more useful products there are and the less waste there is.

Example Calculations

Steam Reforming:

Methane reacts with water in the production of carbon monoxide and hydrogen.

Balanced equation:

{eq}CH_4 \ + \ H_2O \ \underset{}{\rightarrow} \ CO \ + \ 3H_2 {/eq}

The total mass of reactants = 34g

Mass of desired product {eq}\left ( H_2 \right ) {/eq} = 6g

{eq}\% \ Atom \ Economy \ = \ \left ( \dfrac{6}{34} \right ) \ \times \ 100 \\ \% \ Atom \ Economy \ = \ 0.177 \ \times \ 100 \\ \% \ Atom \ Economy \ = \ 17.7\% {/eq}

Electrolysis of water:

Water is split into hydrogen and oxygen.

Balanced equation:

{eq}2H_2O \ \underset{}{\rightarrow} \ 2H_2 \ + \ O_2 {/eq}

The total mass of reactants = 36g

Mass of desired product {eq}\left ( H_2 \right ) {/eq} = 4g

{eq}\% \ Atom \ Economy \ = \ \left ( \dfrac{4}{36} \right ) \ \times \ 100 \\ \% \ Atom \ Economy \ = \ 0.111 \ \times \ 100 \\ \% \ Atom \ Economy \ = \ 11.1\% {/eq}

Between the two, steam reforming has an atom economy of 17.7% while electrolysis has 11.1%. In other words, steam reforming produces less waste in hydrogen production. It underlines the role of atom economy in the efficiency and sustainability of chemical processes.