Redox II | Edexcel A-Level Chemistry (9CH0)
Redox II
- 62 questions
- 4 subtopics
- Paper 1: advanced inorganic and physical chemistry
- Paper 1 and Paper 3
Covers standard electrode potentials and the hydrogen electrode, building and measuring electrochemical cells, using E° values to predict feasibility, and the storage cells, fuel cells and redox titrations that apply them..
It covers standard electrode potentials and the hydrogen electrode, electrochemical cells, emf and cell diagrams, feasibility, the electrochemical series and disproportionation and storage cells, fuel cells and redox titrations.
Sample questions from Redox II
Answer each one closed book first, then open the answer.
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Standard electrode potentials and the hydrogen electrode
What is meant by the standard electrode potential of a half-cell?
Show the answer
The voltage of that half-cell measured relative to the standard hydrogen electrode under standard conditions. -
Standard electrode potentials and the hydrogen electrode
Why is platinum used in the standard hydrogen electrode?
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It is inert and provides a surface for the reaction and a means of electrical contact. -
Electrochemical cells, emf and cell diagrams
At which electrode does reduction occur?
Show the answer
At the positive electrode. -
Electrochemical cells, emf and cell diagrams
By convention, which half-cell is written on the left of a cell diagram?
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The one with the more negative electrode potential (the one being oxidised). -
Feasibility, the electrochemical series and disproportionation
What does a large positive E°cell indicate about the equilibrium constant?
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The equilibrium constant is large, so the reaction goes almost to completion. -
Feasibility, the electrochemical series and disproportionation
What is a disproportionation reaction?
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A reaction in which the same species is simultaneously oxidised and reduced. -
Storage cells, fuel cells and redox titrations
Why is a manganate(VII) titration described as self-indicating?
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Its purple colour is decolourised as it reacts, and the end point is the first permanent pale pink colour. -
Storage cells, fuel cells and redox titrations
How is a storage cell such as a lead–acid cell recharged?
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An external supply applies a voltage greater than the cell's emf in the opposite direction, reversing both electrode reactions. It works because the discharge products stay on the electrodes.
The 4 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Standard electrode potentials and the hydrogen electrode | Recall questions on the standard conditions, on the construction of the standard hydrogen electrode, and on why a reference electrode is needed at all. | 13 |
| Electrochemical cells, emf and cell diagrams | Calculating the standard emf of a cell, which electrode is positive and where oxidation and reduction occur, the salt bridge, writing and reading conventional cell diagrams such as the zinc and copper cell, and assembling electrochemical cells to measure their voltage. | 10 |
| Feasibility, the electrochemical series and disproportionation | Recall questions on predicting the direction of a redox reaction from E° values, on the limits of that prediction, and on identifying disproportionation from the series. | 12 |
| Storage cells, fuel cells and redox titrations | Storage and fuel cells, the hydrogen-oxygen fuel cell electrode reactions with acidic and alkaline electrolytes, the lead–acid cell's emf, discharge and recharging, lithium cells, and manganate(VII) and iodine-thiosulfate titrations with their equations, end points and calculations. | 27 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby topics
Edexcel A-Level Chemistry Active Recall Guide
Every topic, not just this one. 1,534 questions with their answers.