Starter quiz
- What is an electrolyte in the context of electrolysis?
- A gas that facilitates electrical conduction.
- A liquid or aqueous salt solution that contains freely moving ions. ✓
- A solid material that conducts electricity.
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- What is formed when substances dissolve in water?
- A gaseous mixture
- An aqueous solution ✓
- A precipitate
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- How does electrical conductivity in liquids occur?
- Through the absorption of heat by the liquid.
- Through the movement of electrons in the liquid.
- Through the movement of ions in the liquid. ✓
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- Why are inert electrodes used in electrolysis?
- To catalyse the electrolysis process.
- To increase the conductivity of the solution.
- To prevent the electrodes from reacting with the electrolyte. ✓
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- What happens to copper ions during the electrolysis of copper sulfate solution?
- They are oxidised at the anode to form copper oxide.
- They are reduced at the cathode to form copper metal. ✓
- They remain in solution.
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- What are the products at the anode during the electrolysis of brine?
- Chlorine gas ✓
- Hydrogen gas
- Sodium metal
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Exit quiz
- What is the primary function of the cathode in electrolysis?
- It attracts negative ions and facilitates their oxidation.
- It attracts positive ions and facilitates their reduction. ✓
- It generates electric current.
- It allows current to flow through it.
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- What are the observations at the anode during the electrolysis of copper (II) chloride solution?
- Bubbles of chlorine gas are produced. ✓
- Bubbles of oxygen gas are produced.
- Copper metal is deposited.
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- What happens at the cathode during the electrolysis of copper (II) sulfate solution?
- Copper ions gain electrons and are reduced to copper metal. ✓
- Copper ions lose electrons and are oxidised to copper oxide.
- Copper ions remain in solution and do not participate in the reaction.
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- Explain why copper is deposited at the cathode during the electrolysis of copper (II) sulfate solution.
- Copper ions gain electrons at the cathode and are reduced to copper metal. ✓
- Copper ions lose electrons at the cathode and are oxidised to copper oxide.
- Copper ions remain in solution and do not participate in the reaction.
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- During the electrolysis of brine, why is chlorine gas collected at the anode?
- Chloride ions are discharged at the anode, releasing chlorine gas. ✓
- Hydroxide ions are discharged at the anode, releasing chlorine gas.
- Sodium ions are discharged at the anode, releasing chlorine gas.
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- What is the test for oxygen gas?
- The gas turns limewater milky.
- The gas relights a glowing splint. ✓
- The gas burns with a 'pop'.
- The gas forms a white precipitate with acid.
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Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- Electrolysis involves the decomposition / break-down of a substance by passing an electric current.
- Two types of positive ions are in competition at the negative electrode
- Two types of negative ions are in competition at the positive electrode
- There are rules for which substances are discharged at the anode and cathode
- The gases produced during electrolysis can be collected and tested
Common misconception
confusing the electrodes, electrical cables or carbon electrodes having a break in them
Use the PANIC acronym; positive anode negative is cathode. Check all components of the electric circuit.
Keywords
Aqueous solution - formed when a substance is dissolved in water
Electrolyte - a liquid or aqueous salt solution that contains freely moving ions
Electrolysed - when a substance has been broken down by electrolysis
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