📚 IB Chemistry: Types and Writing of Common Redox Reactions | IB化学：常见氧化还原反应的类型与书写
Redox reactions are fundamental to IB Chemistry, involving electron transfer and changes in oxidation number. They underpin many processes from batteries to metabolism.
氧化还原反应是IB化学的基础内容，涉及电子转移和氧化数变化，涵盖从电池到代谢等多种过程。
1. Core Concepts and Definitions | 核心概念与定义
Oxidation is the loss of electrons, while reduction is the gain of electrons. These definitions are part of the electron-transfer model.
氧化是失去电子的过程，还原是获得电子的过程。这些定义属于电子转移模型。
A useful mnemonic is OIL RIG: Oxidation Is Loss, Reduction Is Gain.
常用助记符为OIL RIG：氧化为失电子，还原为得电子。
Redox reactions always occur together; the total number of electrons lost equals the number gained.
氧化与还原总是同时发生；失去的电子总数等于获得的电子总数。
2. Assigning Oxidation Numbers | 氧化数与规则
Oxidation numbers (states) are assigned using standard rules:
氧化数（氧化态）按标准规则分配：
The oxidation number of a free element is 0.
游离态元素的氧化数为0。
The oxidation number of a monatomic ion equals its charge.
单原子离子的氧化数等于其电荷。
Oxygen usually has oxidation number −2, except in peroxides where it is −1.
氧通常为−2，过氧化物中为−1。
Hydrogen is normally +1, but −1 in metal hydrides.
氢通常为+1，但在金属氢化物中为−1。
The sum of oxidation numbers in a neutral compound is 0; in an ion it equals the ion charge.
中性化合物中氧化数总和为0；离子中等于离子电荷。
For example, in H₂SO₄, hydrogen is +1, oxygen is −2, and sulfur must be +6 so that the sum is 0.
例如，在H₂SO₄中，氢为+1，氧为−2，因此硫必须为+6，总和才为0。
3. Identifying Redox Reactions | 识别氧化还原反应
A redox reaction is identified by a change in oxidation number for at least one element.
氧化还原反应的识别依据是至少一种元素的氧化数发生变化。
MgO, magnesium changes from 0 to +2 and oxygen from 0 to −2, so electrons are transferred.
例如，在反应2Mg + O₂ → 2MgO中，镁从0变为+2，氧从0变为−2，因此发生了电子转移。
In contrast, reactions without oxidation number changes (e.g., precipitation) are not redox.
相反，无氧化数变化的反应（如沉淀反应）不属于氧化还原反应。
4. Half-Reactions | 半反应：氧化与还原
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