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Precise Learning Objective |
Linked |
Question / Activity
(Designed for maximum working out) |
Stepping Stones |
Pitstop Check
(Thinking Map) |
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Even though no atoms are gained or lost in a chemical reaction, it is not always possible to obtain the calculated amount of a product because:
??? the reaction may not go to completion because it is reversible
??? some of the product may be lost when it is separated from the reaction mixture;
? some of the reactants may react in ways different to the expected reaction. |
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(Chem only) Suggest why it is not always possible obtain the calculated amount of product from a reaction? 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 amount of a product obtained is known as the yield. |
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(Chem only) What does the term yield refer to? |
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When compared with the maximum theoretical amount as a percentage, it is called the percentage yield.
% Yield = Mass of product actually made / Maximum theoretical mass of product ? 100 |
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(Chem only) What is percentage yield? |
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Students should be able to calculate the percentage yield of a product from the actual yield of a reaction |
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(Chem only) What is the formula for calculating percentage yield? |
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(HT only) calculate the theoretical mass of a product from a given mass of reactant and the balanced equation for the reaction. |
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(Chem only) What mass of carbon dioxide is formed when 12 g of carbon is burned in air? |
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