📚 AQA A Level Chemistry Unit 3 Jan 20 Insert: Essential Data and Practical Skills Guide | AQA A Level 化学 Unit 3 2020年1月数据手册与实验技能指南
The January 2020 AQA A Level Chemistry Unit 3 insert is a data sheet designed to support synoptic problem-solving, practical analysis and quantitative chemistry. It contains standard electrode potentials, infrared and NMR reference data, physical constants and selected equations. This guide explains how to use each part of the insert effectively, while also covering the key practical skills and calculations that Unit 3 questions demand.
2020 年 1 月 AQA A Level 化学 Unit 3 考试插页是一份数据手册，旨在帮助考生完成综合性问题、实验分析和定量计算。插页包含标准电极电势、红外与核磁共振参考数据、物理常数以及部分公式。本指南将详细说明如何使用插页中的每一部分，并覆盖 Unit 3 题目所要求的关键实验技能与计算方法。
1. The Role of the January 2020 Insert | 2020年1月考试插页的作用
The Unit 3 insert is not a question paper; it is a reference tool. You are expected to find relevant data quickly instead of memorising every value. For example, electrode potential questions often require you to select two half-cells from the table and calculate E°cell under standard conditions.
Unit 3 插页不是试卷本身，而是一种参考资料。考试要求你快速查找相关数据，而不是背诵每一个数值。例如，电极电势类题目通常需要你从表格中选取两个半电池，并在标准条件下计算 E°cell。
AQA also includes the periodic table, infrared absorption ranges and proton NMR chemical shift values. Reading the column headings and units carefully is essential, because a unit error can change the answer completely.
AQA 插页还附有周期表、红外吸收范围以及质子核磁共振化学位移值。仔细阅读表格的表头和单位非常重要，因为单位错误可能完全改变答案。
2. Key Constants You Must Be Ready to Use | 必须会用的关键常数
The January 2020 insert lists constants, but you should already know which constant is needed for each type of calculation. Being familiar with their units saves time and prevents errors when substituting into equations.
2020 年 1 月的插页列出了各类常数，但你应该已经知道每种计算需要哪个常数。熟悉这些常数的单位可以节省时间，并避免代入方程时出现错误。
| Constant | Value | Typical use |
|---|---|---|
| Avogadro constant, L | 6.022 × 10²³ mol⁻¹ | Mole and particle calculations |
| Gas constant, R | 8.31 J K⁻¹ mol⁻¹ | Ideal gas equation |
| Specific heat capacity of water, c | 4.18 J g⁻¹ K⁻¹ | Calorimetry |
| Ionic product of water, Kw | 1.00 × 10⁻¹⁴ mol² dm⁻⁶ at 298 K | pH and buffer problems |
When you use these constants, always convert volumes to dm³, temperatures to kelvin and masses to grams if the constant requires those units.
使用这些常数时，必须根据常数的单位要求，把体积换算为 dm³、温度换算为开尔文、质量换算为克。
3. Mole Calculations and the Avogadro Constant | 摩尔计算与阿伏伽德罗常数
Most Unit 3 questions begin with the mole concept. The central equation is n = m ÷ M, where n is the amount in mol, m is mass in g, and M is molar mass in g mol⁻¹.
大多数 Unit 3 题目都从摩尔概念开始。核心公式是 n = m ÷ M，其中 n 表示物质的量（mol），m 表示质量（g），M 表示摩尔质量（g mol⁻¹）。
n = m ÷ M
You can also link moles to the number of particles by multiplying by the Avogadro constant. This is especially common in empirical formula, percentage yield and atom economy questions.
你也可以用阿伏伽德罗常数乘以物质的量来求粒子数。这在经验式、产率和原子经济性题目中尤其常见。
Number of particles = n × 6.022 × 10²³
In solution chemistry, use n = c × V, remembering that V must be in dm³. If the question gives cm³, divide by 1000 first.
在溶液化学中，使用 n = c × V，并记住 V 必须用 dm³。如果题目给的是 cm³，先除以 1000。
4. Ideal Gas Equation and Its Rearrangements | 理想气体方程与变形
The ideal gas equation is widely examined in Unit 3, especially when collecting gases over water or measuring the molar mass of a volatile liquid. The equation is PV = nRT.
理想气体状态方程在 Unit 3 中经常考查，特别是在排水集气法收集气体或测定易挥发液体摩尔质量的实验中。方程为 PV = nRT。
PV = nRT
Always convert pressure to pascals, volume to cubic metres, and temperature to kelvin when using R = 8.31 J K⁻¹ mol⁻¹. If the pressure is given in kPa, multiply by 1000.
当使用 R = 8.31 J K⁻¹ mol⁻¹ 时，必须把压力换算成帕斯卡，体积换算成立方米，温度换算成开尔文。如果压力单位是 kPa，要乘以 1000。
n = PV ÷ RT
Rearranging to find molar mass uses M = mRT ÷ PV. This is useful in the volatile liquid practical, where the mass of vapour, pressure, volume and temperature are measured.
将公式变形可求摩尔质量：M = mRT ÷ PV。这在挥发液体实验中非常有用，实验中需要测量蒸气的质量、压力、体积和温度。
5. Energetics: Calorimetry and Enthalpy Changes | 能量学：量热法与焓变
Calorimetry questions require q = mcΔT, where q is heat energy in J, m is mass of water or solution in g, c is specific heat capacity, and ΔT is the temperature change in K or °C.
量热法题目需要 q = mcΔT，其中 q 表示热量（J），m 表示水或溶液的质量（g），c 表示比热容，ΔT 表示温度变化（K 或 °C）。
q = mcΔT
To find ΔH, divide the heat energy by the moles of the limiting reagent and convert the sign. For exothermic reactions, ΔH is negative; for endothermic reactions, ΔH is positive.
要求 ΔH，必须把热能量除以限制反应物的物质的量，并注意符号。放热反应 ΔH 为负，吸热反应 ΔH 为正。
ΔH = ±q ÷ n
A common error is forgetting to include the mass of both solutions when two solutions are mixed, or using the burner flame position incorrectly in combustion experiments. In January 2020-style questions, look out for heat losses and incomplete combustion as sources of reduced accuracy.
常见错误包括：两种溶液混合时忘记把两种溶液的质量都算进去，或者燃烧实验中酒精灯位置不正确。在 2020 年 1 月风格的题目中，要注意热损失和不完全燃烧会导致准确度下降。
6. Kinetics: Rate Equations and Arrhenius | 动力学：速率方程与阿伦尼乌斯方程
Unit 3 often tests rate experiments, such as following the production of a gas or a colour change. The rate equation links reaction rate to concentrations raised to their orders.
Unit 3 常考查速率实验，例如通过气体生成量或颜色变化来跟踪反应。速率方程将反应速率与浓度（以其反应级数为指数）联系起来。
rate = k[A]ᵐ[B]ⁿ
The overall order is the sum of the individual orders, m + n. You may need to determine orders from initial rates or from concentration-time graphs.
总反应级数是各反应级数之和，即 m + n。你可能需要根据初始速率法或浓度-时间图来确定反应级数。
The insert may supply the Arrhenius equation, which links rate constant k, activation energy Ea and temperature T.
插页可能提供阿伦尼乌斯方程，它将速率常数 k、活化能 Ea 和温度 T 联系起来。
k = Ae–Eₐ/RT
A linear plot of ln k against 1/T has gradient –Ea/R, allowing activation energy to be calculated. Remember to use T in kelvin and R = 8.31 J K⁻¹ mol⁻¹.
以 ln k 对 1/T 作图得到直线，斜率为 –Ea/R，从而可以计算活化能。记住 T 必须用开尔文，R = 8.31 J K⁻¹ mol⁻¹。
7. Chemical Equilibria: Kc and Kp | 化学平衡：Kc 与 Kp
For homogeneous equilibria in solution, Kc is calculated from equilibrium concentrations. For gaseous equilibria, Kp uses partial pressures.
对于溶液中的均相平衡，Kc 由平衡浓度计算；对于气体平衡，Kp 使用分压。
Kc = [C]ᶜ[D]ᵈ ÷ [A]ᵃ[B]ᵇ
The powers are the stoichiometric coefficients from the balanced equation. Pure solids and pure liquids are omitted from the Kc expression.
指数来自配平方程式中的化学计量数。纯固体和纯液体不计入 Kc 表达式。
Kp = p(C)ᶜp(D)ᵈ ÷ p(A)ᵃp(B)ᵇ
Partial pressure is calculated by multiplying the mole fraction by the total pressure. Use the partial pressure symbol p, not square brackets, in Kp expressions.
分压等于摩尔分数乘以总压强。在 Kp 表达式中使用分压符号 p，不要使用方括号。
8. Acid-Base Equilibria, pH and Buffers | 酸碱平衡、pH 与缓冲溶液
The insert supplies Kw and Ka values for many weak acids. You need to convert between pH, hydrogen ion concentration and hydroxide ion concentration correctly.
插页提供了许多弱酸的 Kw 和 Ka 值。你需要正确地进行 pH、氢离子浓度和氢氧根离子浓度之间的换算。
pH = –log₁₀[H⁺]
[H⁺] = 10⁻pH
For a weak acid HA, the acid dissociation constant is Ka = [H⁺][A⁻] ÷ [HA]. At half-neutralisation, pH = pKa, which is a common multiple-choice point.
对于弱酸 HA，酸离解常数 Ka = [H⁺][A⁻] ÷ [HA]。在半中和点时，pH = pKa，这是常见的选择题考点。
Ka = [H⁺][A⁻] ÷ [HA]
Buffer solutions resist changes in pH. The buffer equation is pH = pKa + log₁₀([A⁻] ÷ [HA]). This allows you to calculate the pH after small additions of acid or base.
缓冲溶液能抵抗 pH 的变化。缓冲方程为 pH = pKa + log₁₀([A⁻] ÷ [HA])。这可以用来计算加入少量酸或碱后的 pH。
9. Electrode Potentials and the Electrochemical
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