6.9 Atom Economy

Question 1

What does the atom economy of a reaction tell you?

Answer 1

How much of the mass of the reactants is wasted when manufacturing a chemical and how much ends up as desired products.

Question 2

What is the equation for atom economy?

Answer 2

Relative formula mass of desired products/relative formula mass of all reactants x100

Question 3

Why are reactions with low atom economy bad? (3)

Answer 3

• Reactions with low atom economy use up resources very quickly.
• At the same time, they make lots of waste materials that have to be disposed of somehow. That tends to make these reactions unsustainable - non-renewable raw materials will run out and the waste has to go somewhere.
• For the same reason, low atom economy reactions aren’t usually profitable. Raw materials are often expensive to buy, and waste products can be expensive to remove and dispose of responsibly.

Question 4

How can you counteract reactions with low atom economy?

Answer 4

You could find a use for the waste products rather than just throwing them away. There’s often more than one way to make the product you want, so the trick is to come up with a reaction that gives useful-by-products rather than useless ones.

Question 5

What are the problems with low atom economy?

Answer 5

• It will be less sustainable as it will use more resources
• There will be more waste products which will have to be disposed of

Question 6

Identify 3 other factors, besides atom economy, that should be considered when choosing between two different methods of producing a useful product

Answer 6

Yield, the rate of the reaction and position of equilibrium