amazon.co.ukRedox and Electrochemistry
A-Level Chemistry revision: Redox and Electrochemistry. Learning objectives, key points, worked examples and practice questions across AQA, Edexcel, OCR, WJEC and CCEA.
📌 Key Points
Key Fact: Oxidation = loss of e⁻ (OIL RIG); Oxidation state rules: element=0, Group 1=+1, O=-2 (exc peroxides), H=+1 (exc hydrides)
Key Fact: Half-equations: balance atoms (O with H₂O, H with H⁺), then charge with e⁻
Key Fact: Cell: anode (oxidation) || cathode (reduction); E deg _cell = E deg _red(cathode) - E deg _red(anode)
Key Fact: Feasible if E deg _cell > 0; Equilibrium: E deg _cell = 0.059/n log K at 298K
Key Fact: Nernst: E = E deg - 0.059/n log Q; concentration cells generate voltage from conc difference
Key Fact: Fuel cell: H₂ + ½O₂ -> H₂O; H₂ oxidised at anode, O₂ reduced at cathode; high efficiency
Key Fact: Rechargeable: Li-ion (LiCoO₂/Li), NiMH, lead-acid; reversible redox
🎯 Learning Objectives
- Assign oxidation states using rules
- Balance redox half-equations and full equations in acidic/alkaline conditions
- Understand electrochemical cells: half-cells, salt bridge, cell notation
- Calculate E deg _cell = E deg _cathode - E deg _anode; predict feasibility
- Apply Nernst equation for non-standard conditions
- Understand commercial cells: fuel cells, rechargeable batteries
- Use standard electrode potentials to predict reaction direction
💡 Worked Example
Exam-Style Question
Question: Calculate E deg for: Zn | Zn^2⁺ || Cu^2⁺ | Cu. E deg (Zn^2⁺/Zn) = -0.76V, E deg (Cu^2⁺/Cu) = +0.34V. Is reaction spontaneous?
Model Answer:
E deg _cell = 0.34 - (-0.76) = +1.10 V > 0 -> spontaneous. Zn oxidised (anode), Cu^2⁺ reduced (cathode). Reaction: Zn + Cu^2⁺ -> Zn^2⁺ + Cu
❓ Practice Questions
Questions:
- Balance in acid: MnO₄⁻ + Fe^2⁺ -> Mn^2⁺ + Fe^3⁺
- E deg (Ag⁺/Ag) = +0.80V, E deg (Cu^2⁺/Cu) = +0.34V. Which is stronger oxidising agent?
- Write Nernst equation for Cu | Cu^2⁺(0.1M) || Ag⁺(0.01M) | Ag
- Why can't E deg predict reaction rate?
- Half-reaction for O₂ + 4H⁺ + 4e⁻ in fuel cell
🎬 Video Resources
- Redox and Electrochemistry - Overview -- YouTube Search
- Redox and Electrochemistry - Exam Questions -- YouTube Search
📄 Past Papers & Exam Resources
🔗 Further Reading & Resources
- Physics & Maths Tutor - Redox and Electrochemistry -- Free notes, worksheets, and past paper questions by topic
- Dr Frost Maths - Redox and Electrochemistry -- Free resources, slides, and interactive questions
- BBC Bitesize - Redox and Electrochemistry -- BBC Bitesize revision resources