Edexcel A-Level Chemistry Topic 14.2: Redox II – Electrode Potentials and Electrochemical Cells | Edexcel A-Level 化学 14.2：氧化还原 II——电极电势与电化学电池

📚 Edexcel A-Level Chemistry Topic 14.2: Redox II – Electrode Potentials and Electrochemical Cells | Edexcel A-Level 化学 14.2：氧化还原 II——电极电势与电化学电池

This revision guide covers Edexcel A-Level Chemistry Topic 14.2: Redox II, with emphasis on standard electrode potentials, electrochemical cells, and feasibility predictions. It includes worked examples and common exam pitfalls.

本复习指南覆盖 Edexcel A-Level 化学 14.2：氧化还原 II，重点讲解标准电极电势、电化学电池及反应可行性判断，并配有典型例题与常见考试错误。

1. Redox Foundations and Oxidation Numbers | 氧化还原基础与氧化数

Redox reactions involve electron transfer. Oxidation is loss of electrons; reduction is gain of electrons. Oxidation numbers track how electrons are redistributed in compounds and ions.

氧化还原反应涉及电子转移。氧化是失去电子，还原是得到电子。氧化数用于追踪电子在化合物和离子中的重新分配。

A redox half-equation shows one half of the process. For example, zinc oxidation is Zn → Zn²⁺ + 2e⁻ and copper reduction is Cu²⁺ + 2e⁻ → Cu.

氧化还原半反应式表示反应的一半。例如，锌的氧化为 Zn → Zn²⁺ + 2e⁻，铜的还原为 Cu²⁺ + 2e⁻ → Cu。

2. Half-cells and the Need for a Reference Electrode | 半电池与参比电极的必要性

To compare electron-transfer tendencies, we build half-cells. A metal/metal ion half-cell consists of a metal strip in contact with its aqueous ions, such as Zn²⁺/Zn.

为了比较电子转移倾向，我们构建半电池。金属/金属离子半电池由金属条与其金属离子溶液接触构成，例如 Zn²⁺/Zn。

Individual half-cell potentials cannot be measured absolutely. We measure them relative to a standard reference, the standard hydrogen electrode.

单个半电池电势无法绝对测量。我们以标准氢电极作为标准参比来测量。

3. The Standard Hydrogen Electrode (SHE) | 标准氢电极 (SHE)

The standard hydrogen electrode (SHE) uses hydrogen gas at 100 kPa bubbling over platinum foil in 1.00 mol dm⁻³ H⁺ at 298 K.

标准氢电极 (SHE) 使用 100 kPa 氢气，在铂箔上与 1.00 mol dm⁻³ H⁺ 溶液在 298 K 下平衡。

2H⁺(aq) + 2e⁻ ⇌ H₂(g) E° = 0.00 V

The electrode potential of the SHE is defined as 0.00 V, and all other standard electrode potentials are measured relative to it.

SHE 的电极电势被规定为 0.00 V，所有其他标准电极电势都是相对它测得的。

The platinum surface provides a conductive, inert surface

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