| Method |
Precise Learning Objective |
Linked |
Question / Activity
(Designed for maximum working out) |
Stepping Stones |
Pitstop Check
(Thinking Map) |
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When an ionic compound is melted or dissolved in water, the ions are free to move about within the liquid or solution. These liquids and solutions are able to conduct electricity and are called electrolytes. |
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When is an ionic compound able to conduct electricity? |
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(HT only) Write balanced half equations and ionic equations where appropriate. |
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(HT) What is the balanced half equation for H ? e??? H2 |
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Passing an electric current through electrolytes causes the ions to move to the electrodes. Positively charged ions move to the negative electrode (the cathode), and negatively charged ions move to the positive electrode (the anode). Ions are discharged at the electrodes producing elements. This process is called electrolysis. |
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What happens at each of the electrodes in electrolysis when an electric current is passed through the electroytes? Class practical:
electrolysis of copper sulfate |
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(HT only) Throughout Section 4.4.3 Higher Tier 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. (MS) |
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(HT) What happens at the anode and cathode electrodes in the electrolysis of aqueous sodium chloride? (use half equations to help explain) |
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When a simple ionic compound (eg lead bromide) is electrolysed in the molten state using inert electrodes, the metal (lead) is produced at the cathode and the non-metal (bromine) is produced at the anode. |
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Which electrode as the metals and non metals products found during electrolysis? |
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Students should be able to predict the products of the electrolysis of binary ionic compounds in the molten state. |
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What would the products be for the electrolysis of the following ionic compounds:
1. NaCl
2. PbBr2
3. NaOH
4. Al2O3 |
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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) What would the half equations be for the electrolysis of NaCl? |
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During electrolysis, at the cathode (negative electrode), positively charged ions gain electrons and so the reactions are reductions. |
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What happens at the cathode during electrolysis? Is this an oxidation or reduction reaction? |
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At the anode (positive electrode), negatively charged ions lose electrons and so the reactions are oxidation reactions. |
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What happens at the anode during electrolysis? Is this an oxidation or reduction reaction? |
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Reactions at electrodes can be represented by half equations, for example:
2H 2e- ? H2
and
4OH- ? O2 2H2O 4e-
or
4OH- 4e- ? O 2H2O |
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What would the half equations be during the electrolysis of PbBr2? |
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