| Method |
Precise Learning Objective |
Linked |
Question / Activity
(Designed for maximum working out) |
Stepping Stones |
Pitstop Check
(Thinking Map) |
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The ions discharged when an aqueous solution is electrolysed using inert electrodes depend on the relative reactivity of the elements involved. |
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Why is hydrogen produced instead of sodium in the electrolysis of NaCl solution? |
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At the negative electrode (cathode), hydrogen is produced if the metal is more reactive than hydrogen. |
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When is hydrogen produced at the negative electrode in electrolysis? |
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At the positive electrode (anode), oxygen is produced unless the solution contains halide ions when the halogen is produced. |
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When is oxygen not produced at the positive electrode? |
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This happens because in the aqueous solution water molecules break down producing hydrogen ions and hydroxide ions that are discharged. |
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Why are hydrogen and oxygen often discharged in the electrolysis of aqueous ionic solutions? Demo:
Rainbow electrolysis
http://www.rsc.org/learn-chemistry/resource/res00000735/colourful-electrolysis?cmpid=CMP00004981 |
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Students should be able to predict the products of the electrolysis of aqueous solutions containing a single ionic compound. |
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What are the three products made in the electrolysis of aqueous sodium chloride? Class:
Electrolysis of NaCl to identify unexpected products |
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(HT only) students should be able to write half equations for the reactions occurring at the electrodes during electrolysis, and may be required to complete and balance supplied half equations for this process . (MS) |
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(HT) |
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