| Method |
Precise Learning Objective |
Linked |
Question / Activity
(Designed for maximum working out) |
Stepping Stones |
Pitstop Check
(Thinking Map) |
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Some reactions may appear to involve a change in mass but this can usually be explained because a reactant or product is a gas and its mass has not been taken into account. For example: when a metal reacts with oxygen the mass of the oxide produced is greater than the mass of the metal or in thermal decompositions of metal carbonates carbon dioxide is produced and escapes into the atmosphere leaving the metal oxide as the only solid product. |
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When a gas is produced in a chemical reaction, why would the mass of the products appear to be less than that of the reactants? Extended writing: use measurements of mass before and after an experiment to explain what has happened to the mass during the experiment and why it has happened. |
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Students should be able to explain any observed changes in mass in non-enclosed systems during a chemical reaction given the balanced symbol equation for the reaction and explain these changes in terms of the particle model. |
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Explain why in the reaction below the mass of the products would be greater than that of the reactants
2Mg (s) O2 (g) -> 2MgO (s) |
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Whenever a measurement is made there is always some uncertainty about the result obtained. |
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What does the term uncertainty mean? |
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Students should be able to represent the distribution of results and make estimations of uncertainty |
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How would you represent the distrubtion of results to make estimations of uncertainty? |
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Students should be able to use the range of a set of measurements about the mean as a measure of uncertainty. |
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A pippette has an uncertainty of /-0.01mL. It is used three times in a practical. What is the mean measure of uncertainty? |
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