📚 Edexcel A-Level Chemistry Topic 16: Kinetics II | 爱德思 A-Level 化学：专题 16 动力学 II
Kinetics II builds on AS-level ideas by linking experimental rate data to reaction mechanisms. You must be able to determine orders of reaction, calculate the rate constant k and its units, use half-life equations, and apply the Arrhenius equation to activation energy.
动力学 II 在 AS 阶段的基础上，将实验速率数据与反应机理联系起来。你必须掌握反应级数的确定、速率常数 k 及其单位、半衰期公式，以及用阿伦尼乌斯方程处理活化能。
1. Rate Equations and Orders of Reaction | 速率方程与反应级数
For a reaction A + B → products, the rate equation is normally written as r = k[A]ᵐ[B]ⁿ, where m and n are the orders with respect to A and B, and k is the rate constant.
对于反应 A + B → 产物，速率方程通常写作 r = k[A]ᵐ[B]ⁿ，其中 m 和 n 分别是关于 A 和 B 的反应级数，k 是速率常数。
The overall order is m + n. Orders are not necessarily equal to stoichiometric coefficients; they must be determined experimentally.
总反应级数为 m + n。反应级数不一定等于化学计量系数，必须通过实验测定。
2. The Rate Constant k and Its Units | 速率常数 k 及其单位
The units of k depend on the overall order of reaction. You can rearrange the rate equation to find units: k = rate ÷ (concentration units)overall order.
k 的单位取决于总反应级数。可以重组速率方程得到单位：k = 速率 ÷（浓度单位）总级数。
| Overall order | Units of k |
|---|---|
| 0 | mol dm⁻³ s⁻¹ |
| 1 | s⁻¹ |
| 2 | mol⁻¹ dm³ s⁻¹ |
| 3 | mol⁻² dm⁶ s⁻¹ |
Learn the pattern: for overall order n, units are mol¹⁻ⁿ dm³ⁿ⁻³ s⁻¹, where concentration is in mol dm⁻³.
记住规律：总级数为 n 时，单位为 mol¹⁻ⁿ dm³ⁿ⁻³ s⁻¹，其中浓度单位为 mol dm⁻³。
3. Initial Rates Method | 初始速率法
To determine the order with respect to a reactant, compare experiments where only that reactant concentration changes. If doubling [A] doubles the initial rate, the order is 1; if it quadruples the rate, the order is 2; if it has no effect, the order is 0.
要确定某反应物的级数，比较只有该反应物浓度变化的实验。如果 [A] 加倍使初始速率
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