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Year 12 Edexcel Chemistry: Formula & Theorem Quick Reference Handbook | Year 12 Edexcel 化学：公式定理速查手册

2026-07-21 09:44 · 本文部分内容由AI辅助创作

📚 Year 12 Edexcel Chemistry: Formula & Theorem Quick Reference Handbook | Year 12 Edexcel 化学：公式定理速查手册

This quick reference handbook brings together all the essential formulas, equations and key definitions from the Year 12 Edexcel Chemistry specification. Designed for rapid revision, it covers quantitative chemistry, energetics, kinetics, equilibrium and redox in one compact resource. Every formula is presented in an easy-to-spot format, with clear worked applications and units.

这本速查手册汇集了 Year 12 Edexcel 化学考纲中所有核心公式、方程式和关键定义。为快速复习而设计，它将计量化学、能量学、动力学、平衡和氧化还原浓缩为一体。每个公式都以醒目的方式呈现，并配有清晰的应用说明和单位。

1. The Mole, Molar Mass and Molar Volume | 摩尔、摩尔质量与摩尔体积

species contains exactly 6.02 × 10²³ particles, a value known as the Avogadro constant, L.

摩尔是物质的量的 SI 单位。1 摩尔任何物质恰好含有 6.02 × 10²³ 个粒子，这个数值被称为阿伏伽德罗常数，L。

L = 6.02 × 10²³ mol⁻¹

The number of moles n is obtained by dividing the total number of entities N by L.

摩尔数 n 可通过粒子总数 N 除以 L 获得。

n = N / L

From mass data, use the molar mass M (in g mol⁻¹). The mass m must be in grams.

由质量数据计算时，使用摩尔质量 M（单位 g mol⁻¹）。质量 m 必须用克为单位。

n = m / M

For gases at room temperature and pressure (RTP, 298 K and 100 kPa), one mole occupies 24 dm³. This gives a quick conversion for gas volumes measured in dm³ at RTP.

对于在室温常压（RTP，298 K，100 kPa）下的气体，1 摩尔占据 24 dm³。这为在 RTP 下测量的气体体积提供了快速换算。

n = V(gas) / 24 (V in dm³ at RTP)

2. Empirical and Molecular Formulae | 经验式与分子式

The empirical formula shows the simplest whole-number ratio of atoms in a compound. It is determined by converting percentage or mass composition into moles, then dividing by the smallest number of moles.

经验式表示化合物中原子的最简整数比。其确定方法是将质量或百分组成换算为摩尔数，然后除以最小的摩尔数。

Step: mass ⟶ moles ⟶ ratio ⟶ whole numbers

The molecular formula gives the actual number of atoms of each element in one molecule. It is always an integer multiple of the empirical formula.

分子式表示一分子中每种原子的实际数量。它总是经验式的整数倍。

Molecular formula = (Empirical formula) × n
n = relative molecular mass / empirical formula mass

CH₂ and the relative molecular mass is 56, n = 56/14 = 4, giving a molecular formula C₄H₈.

例如，若经验式为 CH₂ 且相对分子质量为 56，则 n = 56/14 = 4，得到分子式 C₄H₈。

3. The Ideal Gas Equation | 理想气体状态方程

The ideal gas equation links pressure, volume, temperature and number of moles. It is the most accurate way to relate gas measurements under non-standard conditions.

理想气体状态方程将压强、体积、温度与摩尔数联系起来。这是非标准条件下气体计算最准确的方法。

pV = nRT

p is pressure in pascals (Pa), V is volume in cubic metres (m³), n is amount in mol, T is temperature in kelvin (K). The gas constant R has the value 8.31 J mol⁻¹ K⁻¹.

p 是压强（Pa），V 是体积（m³），n 是物质的量（mol），T 是温度（K）。气体常数 R 的值为 8.31 J mol⁻¹ K⁻¹。

1 × 10⁻³ m³, 1 cm³ = 1 × 10⁻⁶ m³. Pressures in kPa must be multiplied by 1000 to give Pa.

务必换算体积：1 dm³ = 1 × 10⁻³ m³，1 cm³ = 1 × 10⁻⁶ m³。以 kPa 为单位的压强需乘以 1000 转换为 Pa。

4. Enthalpy Changes: q = mcΔT and Hess's Law | 焓变：q = mcΔT 与赫斯定律

In a calorimetry experiment, the heat change q is calculated from the mass of the solution, its specific heat capacity and the temperature rise.

在量热实验中，热量变化 q 由溶液质量、比热容和温升计算得出。

q = mcΔT

m is the mass of water or solution (g), c is the specific heat capacity (4.18 J g⁻¹ °C⁻¹ for water), ΔT is the temperature change (°C).

m 是水或溶液的质量（g），c 是比热容（水的 c = 4.18 J g⁻¹ °C⁻¹），ΔT 是温度变化（°C）。

iting reactant. The negative sign indicates that heat lost by the reaction raises the temperature.

每摩尔焓变则为 ΔH = -q / n，其中 n 是限制反应物的摩尔数。负号表示反应放出的热量使温度升高。

Hess's Law states that the total enthalpy change of a reaction is independent of the route taken. For formation data:

赫斯定律指出，反应的总焓变与反应路径无关。使用生成焓数据时：

ΔH = ΣΔHf°(products) - ΣΔHf°(reactants)

For combustion data, the expression reverses:

使用燃烧焓数据时，表达式相反：

ΔH = ΣΔHc°(reactants) - ΣΔHc°(products)

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5. Bond Enthalpies | 键焓

Bond enthalpy is the energy required to break one mole of a specific covalent bond in the gaseous state. Mean bond enthalpies are averages over a range of compounds.

键焓是在气态下断裂 1 摩尔某特定共价键所需的能量。平均键焓是多个化合物中的平均值。

ΔH ≈ Σ E(bonds broken) - Σ E(bonds formed)

Energy must be supplied to break bonds (endothermic, positive), and energy is released when bonds form (exothermic, negative). The sign in the formula automatically gives the net enthalpy change.

断键需要吸收能量（吸热，正值），成键则释放能量（放热，负值）。公式中的符号自动给出净焓变。

broken: 1 H-H and 1 Cl-Cl; bonds formed: 2 H-Cl. ΔH = [E(H-H) + E(Cl-Cl)] - [2 × E(H-Cl)].

例如在反应 H₂ + Cl₂ → 2HCl 中，断裂的键：1 个 H-H 和 1 个 Cl-Cl；生成的键：2 个 H-Cl。ΔH = [E(H-H) + E(Cl-Cl)] - [2 × E(H-Cl)]。

6. Rate Equations and Orders of Reaction | 速率方程与反应级数

The rate of a reaction can be expressed as a rate equation which shows how the rate depends on the concentrations of reactants. The proportionality constant is the rate constant k.

反应速率可以用速率方程表达，显示速率如何依赖于反应物浓度。比例常数即为速率常数 k。

rate = k [A]m [B]n

The powers m and n are the orders with respect to A and B. The overall order is m + n. Zero‑order reactions have a constant rate; first‑order reactions show a half‑life that does not depend on initial concentration.

指数 m 和 n 分别是相对于 A 和 B 的反应级数，总级数为 m + n。零级反应速率恒定；一级反应的半衰期与初始浓度无关。

t½ = ln 2 / k (first order only)

The units of k depend on the overall order. They are determined by rearranging the rate equation.

k 的单位取决于总反应级数，可由速率方程的量纲推导。

Overall orderUnits of k
0mol dm⁻³ s⁻¹
1s⁻¹
2dm³ mol⁻¹ s⁻¹

7. The Equilibrium Constant Kc | 平衡常数 Kc

For a reversible reaction at equilibrium, the equilibrium constant Kc is defined in terms of the concentrations of products and reactants, each raised to the power of its stoichiometric coefficient.

对于达到平衡的可逆反应，平衡常数 Kc 由产物和反应物的平衡浓度定义，各浓度以其计量系数为指数。

aA + bB ⇌ cC + dD
Kc = [C]c [D]d / [A]a [B]b

Solids and pure liquids are omitted from the expression because their concentrations are constant. Kc changes only with temperature; it is unaffected by catalysts or changes in pressure.

固体和纯液体不写入表达式，因为它们的浓度不变。Kc 仅随温度变化；催化剂或压强改变不影响其数值。

A large Kc means the equilibrium lies to the right (products favoured); a small Kc means the equilibrium lies to the left (reactants favoured).

Kc 值大表示平衡偏向右侧（产物为主）；Kc 值小表示平衡偏向左侧（反应物为主）。

8. pH and the Ionic Product of Water Kw | pH 与水的离子积 Kw

The pH scale is a logarithmic measure of the hydrogen ion concentration.

pH 标度是对氢离子浓度的对数度量。

pH = -log[H⁺]

Conversely, [H⁺] = 10-pH. Water undergoes slight self‑ionisation, giving the ionic product Kw.

反之，[H⁺] = 10⁻ᵖᴴ。水有微弱的自偶电离，产生离子积 Kw。

H₂O ⇌ H⁺ + OH⁻
Kw = [H⁺][OH⁻] = 1.0 × 10⁻¹⁴ mol² dm⁻⁶ (at 298 K)

In pure water and neutral solutions, [H⁺] = [OH⁻] = √Kw = 1.0 × 10⁻⁷ mol dm⁻³, giving pH 7.

在纯水和中性溶液中，[H⁺] = [OH⁻] = √Kw = 1.0 × 10⁻⁷ mol dm⁻³，对应 pH 7。

For a strong base, [OH⁻] = base concentration, then [H⁺] = Kw / [OH⁻] and pH can be found.

对于强一元酸，[H⁺] = 酸的浓度。对于强碱，[OH⁻] = 碱的浓度，然后 [H⁺] = Kw / [OH⁻] 可求 pH。

9. Oxidation Numbers and Redox | 氧化数与氧化还原

Oxidation numbers are used to track electron transfers in redox reactions. They are assigned according to a set of rules.

氧化数用来追踪氧化还原反应中的电子转移。根据一套规则进行赋值。