📚 More about Electrolysis | 深入探究电解
Electrolysis is a fundamental redox process in which electrical energy from an external power supply drives a non-spontaneous chemical reaction. This article moves beyond basic cell diagrams to explore the quantitative treatment, competing electrode reactions, and large-scale applications that frequently appear in Cambridge A-Level examinations.
电解是利用外部电源提供的电能驱动非自发化学反应的基本氧化还原过程。本文将超越基础电解池示意图，探讨定量处理方法、竞争电极反应以及剑桥 A-Level 考试中经常出现的大规模工业应用。
1. Quick Recap of Electrolytic Cells | 电解池快速回顾
In an electrolytic cell, the positive electrode is the anode and the negative electrode is the cathode. Oxidation always occurs at the anode, while reduction always occurs at the cathode. The electrolyte must contain mobile ions, either as a molten ionic compound or as an aqueous solution.
在电解池中，正极是阳极，负极是阴极。氧化反应总是发生在阳极，还原反应总是发生在阴极。电解质必须含有可自由移动的离子，可以是熔融离子化合物或水溶液。
Electrons are forced onto the cathode by the external power supply, making it electron-rich. At the anode, electrons are withdrawn and returned to the power supply. This continuous movement of electrons in the external circuit is the electric current.
外部电源将电子强行推送到阴极，使其富电子；在阳极，电子被抽走并回到电源。外电路中电子的持续定向移动形成了电流。
Key terminology includes cathode, anode, electrolyte, discharge, inert electrodes and active electrodes. Inert electrodes, such as graphite or platinum, do not take part in the electrode reactions; active electrodes, such as copper, can be oxidised.
关键术语包括阴极、阳极、电解质、放电、惰性电极和活泼电极。石墨或铂等惰性电极不参与电极反应；铜等活泼电极本身可被氧化。
2. Faraday's Laws of Electrolysis | 法拉第电解定律
Michael Faraday showed that the quantity of chemical change at an electrode is proportional to the quantity of electricity passed through the cell. This is the basis of all quantitative electrolysis calculations.
迈克尔·法拉第证明，电极上发生化学变化的量与通过电解池的电量成正比。这是所有定量电解计算的基础。
The first law can be written as:
第一定律可以表示为：
m ∝ Q
where m is the mass deposited or dissolved and Q is the total electric charge. The second law states that the amounts of different substances liberated by the same quantity of electricity are proportional to their equivalent masses.
其中 m 是沉积或溶解的质量，Q 是总电荷量。第二定律指出，相同电量析出的不同物质的量与它们的化学当量质量成正比。
For A-Level work, the most useful form combines both laws: one mole of electrons carries 96 500 coulombs of charge. This allows us to convert current and time into moles of electrons, and then into moles of product.
在 A-Level 学习中，最有用的形式是将两条定律结合：1 摩尔电子带有 96 500 库仑电荷。这样我们就能将电流和时间转换为电子的物质的量，再转换为产物的物质的量。
3. The Faraday Constant and Moles of Electrons | 法拉第常数与电子摩尔数
The Faraday constant, F, is the electric charge carried by one mole of electrons. Its numerical value is 96 500 C mol⁻¹, and it is usually given in the Cambridge data sheet.
法拉第常数 F 是 1 摩尔电子所带的电荷量，数值为 96 500 C mol⁻¹，通常在剑桥数据表中给出。
The charge Q passing through a circuit is calculated from current I and time t:
通过电路的电荷量 Q 由电流 I 和时间 t 计算：
Q = I × t
where Q is in coulombs (C), I is in amperes (A) and t is in seconds (s). Do not forget to convert minutes or hours into seconds before calculating.
其中 Q 的单位为库仑 (C)，I 为安培 (A)，t 为秒 (s)。计算前不要忘记将分钟或小时换算成秒。
The amount of electrons, n(e⁻), is therefore:
因此电子的物质的量 n(e⁻) 为：
n(e⁻) = Q / F = (I × t) / 96 500
This one expression
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