| Method |
Precise Learning Objective |
Linked |
Question / Activity
(Designed for maximum working out) |
Stepping Stones |
Pitstop Check
(Thinking Map) |
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The atom economy (atom utilisation) is a measure of the amount of starting materials that end up as useful products. |
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(Chem only) What is atom economy a measure of? Describe how atoms are lost or gained in a chemical reaction.
Explain why atoms can be lost or gained in a chemical reaction.
Calculate the theoretical yield for simple examples.
Extended writing: write instructions to another student how to calculate the theoretical yield giving explained examples.
Use Lego as a model for chemical reactions demonstrating the loss of product and use the model as a simple introduction to yield calculations.
The same can be applied to atom economy. |
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The percentage atom economy of a reaction is calculated using the balanced equation for the reaction as follows: Relative formula mass of desired product from equation / Sum of relative formula masses of all reactants from equation ? 100
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(Chem only) What is the formula for calculating percentage atom economy? |
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Students should be able to calculate the atom economy of a reaction to form a desired product from the balanced equation |
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(Chem only) Hydrazine (N2H4) is used in some rocket fuels. Two different methods can be used to manufacture hydrazine. The reactions are:
NH2Cl NH3 ? N2H4 HCl
2NH3 H2O2 ? N2H4 2H2O
Calculate the atom economy for each reaction |
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(HT only) explain why a particular reaction pathway is chosen to
produce a specified product given appropriate data such as atom
economy (if not calculated), yield, rate, equilibrium position and
usefulness of by-products. |
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(Chem only) How can a chemist in a chemical plant that makes rocket fuel prevent waste products being formed? |
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