Percentage Atom Economy | A Level Chemistry | OCR, AQA, Edexcel

Our A-Level Chemistry Experts are here to help you ace A-Level Chemistry!

This week we are revising Percentage Atom Economy

A-Level Chemistry can be tough but fortunately we’ve made this tutorial to help you score the A* you need for questions on everything to do with Percentage Atom Economy.

A by-product is a secondary product made during the synthesis of another product.
The percentage atom economy is the way to measure how much of thereacting particles become the desired products in a reaction. The desired products exclude the by-products.

The % yield of a reaction depends on the specific experiment – e.g. the same reaction might have 98% yield in an industrial plant, but a 30% yield in a school laboratory. % yield doesn’t consider side products.

The % atom economy is based on the equation. It is a measure of how much of the reactants (in terms of mass) is being converted into desired product. % atom economy does consider side products.
A reaction might have a low atom economy, which means that it produce little of the desired product in the equation, but still could have a 100% efficiency.
A high % yield does not always mean the reaction is efficient. When a reaction has a high percentage yield it means that the actual yield of the product is very close to the theoretical yield of the product. However this would still be true if the majority of the reactants formed by-products instead of the desired product.
The higher the % atom economy, the cheaper the process. The process of a reaction with a high percentage atom economy is less expensive because less time and machinery is needed to separate the desired product from the by-products and waste.
The higher the % atom economy, the ‘greener’ the process. If the atom economy of a reaction is high, it means that it is more environmentally friendly because less waste is produced. These reactions are more sustainable because they use raw materials which are renewable and will never run out. This is one of the main reasons why the chemical industry encourages processes with high atom economies.
In the AQA exam, you could be asked to calculate the percentage atom economy of a reaction from a balanced equation.