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

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

This quick reference handbook covers every essential formula, equation, and theorem you need for the SQA Higher Chemistry course. Whether you are revising mole calculations, thermochemistry, equilibrium, or organic functional groups, the key relationships are presented side by side in English and Chinese for rapid retrieval and bilingual understanding.

这本速查手册涵盖了 SQA 高等化学课程中所有核心公式、方程式和定理。不论你是在复习摩尔计算、热化学、平衡还是有机官能团，所有关键关系都以中英对照的形式呈现，方便快速查阅和双语学习。

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1. Mole Concept and Molar Mass | 摩尔概念与摩尔质量

f a chemical to the number of particles. One mole contains 6.02 × 10²³ particles (Avogadro's constant, N_A).

物质的量 (n) 把化学品的质量与粒子数目联系起来。1 摩尔含有 6.02 × 10²³ 个粒子（阿伏伽德罗常数 N_A）。

n = m ÷ M

n = N ÷ N_A

mount of substance (mol), m = mass (g), M = molar mass (g mol⁻¹), N = number of particles.

n = 物质的量 (mol)，m = 质量 (g)，M = 摩尔质量 (g mol⁻¹)，N = 粒子数目。

Molar mass (M) is the mass of one mole of a substance; it is numerically equal to the relative formula mass (M_r) but has units of g mol⁻¹.

摩尔质量 (M) 是 1 摩尔物质的质量，其数值等于相对式量 (M_r)，但单位为 g mol⁻¹。

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2. Concentration, Dilution and Molarity | 浓度、稀释与摩尔浓度

Concentration describes how much solute is dissolved in a given volume of solution. The standard unit is mol dm⁻³ (molarity, c).

浓度表示在一定体积溶液中溶解了多少溶质，常用单位为 mol dm⁻³（摩尔浓度，c）。

c = n ÷ V

c = concentration (mol dm⁻³), n = amount of solute (mol), V = volume of solution (dm³).

c = 浓度 (mol dm⁻³)，n = 溶质的物质的量 (mol)，V = 溶液体积 (dm³)。

When diluting a solution, the number of moles of solute remains unchanged: c₁V₁ = c₂V₂.

稀释溶液时，溶质的物质的量保持不变：c₁V₁ = c₂V₂。

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3. Ideal Gas Equation | 理想气体方程

The ideal gas equation relates pressure, volume, temperature and the amount of gas. It is a cornerstone of physical chemistry.

理想气体方程将压力、体积、温度和气体的物质的量联系起来，是物理化学的基石。

pV = nRT

(m³), n = amount of gas (mol), R = 8.314 J K⁻¹ mol⁻¹ (gas constant), T = temperature (K).

p = 压力 (Pa)，V = 体积 (m³)，n = 气体物质的量 (mol)，R = 8.314 J K⁻¹ mol⁻¹（气体常数），T = 温度 (K)。

Molar volume at standard temperature and pressure (STP, 273 K & 100 kPa): V_m ≈ 22.7 dm³ mol⁻¹.

在标准状况下 (STP, 273 K 和 100 kPa)，摩尔体积 V_m 约为 22.7 dm³ mol⁻¹。

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

Empirical formula shows the simplest whole-number ratio of atoms in a compound; molecular formula gives the actual number of atoms of each element in a molecule.

经验式表示化合物中原子的最简整数比；分子式给出一个分子中各元素原子的实际数目。

Molecular formula = (Empirical formula) ×n, where n = M_r(molecular) ÷ M_r(empirical).

分子式 = (经验式) × n，其中 n = 分子式的 M_r ÷ 经验式的 M_r。

To find the empirical formula, convert % composition to masses, then to moles, and divide by the smallest number of moles.

求经验式时，将各元素的质量分数换算为质量，再换算为物质的量，并除以最小的物质的量。

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5. Stoichiometry and Limiting Reactants | 化学计量与限量反应物

Stoichiometry uses the mole ratio from a balanced equation to calculate masses, volumes and concentrations.

化学计量利用配平方程式中的摩尔比来计算质量、体积和浓度。

Limiting reactant is the one that is completely used up first and determines the maximum amount of product formed.

限量反应物是最先被完全消耗的那个反应物，它决定了产物的最大产量。

Theoretical yield = mass of product calculated from the limiting reactant. % yield = (actual yield ÷ theoretical yield) × 100.

理论产量 = 根据限量反应物计算得到的产物质量。产率 = (实际产量 ÷ 理论产量) × 100。

product ÷ total mass of all reactants) × 100; a higher value indicates a greener process.

原子经济性 = (目标产物质量 ÷ 所有反应物总质量) × 100；数值越高，过程越绿色环保。

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6. Enthalpy Changes and Hess's Law | 焓变与盖斯定律

Enthalpy change (ΔH) is the heat energy change at constant pressure. Standard conditions are 100 kPa, 298 K and 1 mol dm⁻³.

焓变 (ΔH) 是恒压下的热能量变化。标准条件为 100 kPa、298 K 和 1 mol dm⁻³。

ΔH = H_products − H_reactants

Exothermic reactions release heat (ΔH negative); endothermic reactions absorb heat (ΔH positive).

放热反应释放热量 (ΔH 为负)；吸热反应吸收热量 (ΔH 为正)。

Hess's Law: the total enthalpy change for a reaction is independent of the route taken, as long as initial and final states are the same.

盖斯定律：只要始态和终态相同，反应的总焓变与途径无关。

Typical ΔH types: formation, combustion, neutralisation, solution. Calculate unknown ΔH by constructing a Hess cycle or by using ΣΔH_f of products − ΣΔH_f of reactants.

常见 ΔH 类型：生成焓、燃烧焓、中和焓、溶解焓。通过构建盖斯循环或利用 ΣΔH_f(产物) − ΣΔH_f(反应物) 计算未知 ΔH。

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7. Gibbs Free Energy and Feasibility | 吉布斯自由能与反应可行性

Gibbs free energy (ΔG) determines whether a reaction is thermodynamically feasible at a given temperature.

吉布斯自由能 (ΔG) 决定反应在给定温度下是否热力学可行。

ΔG = ΔH − TΔS

(kJ mol⁻¹), ΔH = enthalpy change, T = temperature (K), ΔS = entropy change (kJ K⁻¹ mol⁻¹).

ΔG = 自由能变化 (kJ mol⁻¹)，ΔH = 焓变，T = 温度 (K)，ΔS = 熵变 (kJ K⁻¹ mol⁻¹)。

ΔG > 0, the reaction is not feasible under those conditions. ΔG = 0 indicates equilibrium.

当 ΔG < 0 时反应可行；ΔG > 0 则在相应条件下不可行；ΔG = 0 表示处于平衡状态。

ΔH sign	ΔS sign	Feasibility
−	+	Always feasible
+	−	Never feasible
−	−	Feasible at low T
+	+	Feasible at high T

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8. Chemical Equilibrium and Le Chatelier's Principle | 化学平衡与勒夏特列原理

At equilibrium, the rates of forward and reverse reactions are equal. The equilibrium constant K_c is expressed in terms of concentrations.

达到平衡时，正逆反应速率相等。平衡常数 K_c 用浓度表示。

aA + bB ⇌ cC + dD

K_c = [C]^c[D]^d / ([A]^a[B]^b)

Le Chatelier's Principle: if a system at equilibrium is subjected to a change in concentration, pressure or temperature, the equilibrium shifts to oppose the change.

勒夏特列原理：若平衡体系受到浓度、压力或温度的变化，平衡会向抵消该变化的方向移动。

• Increase reactant concentration → shifts right. | 增加反应物浓度 → 向右移动。
• Increase pressure → shifts to side with fewer gas molecules. | 增大压力 → 向气体分子数较少的一方移动。
• Increase temperature → shifts in endothermic direction. | 升高温度 → 向吸热方向移动。
• Catalysts do not affect K_c; they only speed up attainment of equilibrium. | 催化剂不影响 K_c，只加快达到平衡。

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9. Acid-Base Equilibria: pH, pKa, Kw | 酸碱平衡：pH, pKa, Kw

The pH scale quantifies acidity: pH = −log₁₀[H⁺] (H⁺ concentration in mol dm⁻³).

pH 标度衡量酸度：pH = −log₁₀[H⁺]（H⁺ 浓度为 mol dm⁻³）。

Ionic product of water at 298 K: K_w = [H⁺][OH⁻] = 1.0 × 10⁻¹⁴ mol² dm⁻⁶.

298 K 时水的离子积：K_w = [H⁺][OH⁻] = 1.0 × 10⁻¹⁴ mol² dm⁻⁶。

For a weak acid HA ⇌ H⁺ + A⁻, the acid dissociation constant is K_a = [H⁺][A⁻] / [HA], and pK_a = −log₁₀K_a.

对于弱酸 HA ⇌ H⁺ + A⁻，酸解离常数 K_a = [H⁺][A⁻] / [HA]，且 pK_a = −log₁₀K_a。

Approximation for weak acids: [H⁺] ≈ √K_a × c where c is the initial acid concentration. This is valid when dissociation is small (<5%).

弱酸近似公式：[H⁺] ≈ √K_a × c，其中 c 为酸的初始浓度。该式在解离度很小时适用 (<5%)。

es in pH; they contain a weak acid and its salt (or weak base and its salt). The Henderson–Hasselbalch equation: pH = pK_a + log₁₀([A⁻] / [HA]).

缓冲溶液能抵抗 pH 变化；由弱酸及其盐（或弱碱及其盐）组成。亨德森–哈塞尔巴尔赫方程：pH = pK_a + log₁₀([A⁻] / [HA])。

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10. Redox Reactions and Electrochemical Cells | 氧化还原反应与原电池

Oxidation is the loss of electrons; reduction is the gain of electrons. OIL RIG (Oxidation Is Loss, Reduction Is Gain).

氧化是失去电子，还原是得到电子。OIL RIG 记忆法。

Oxidation numbers help identify redox processes: elements in their natural state have oxidation number 0; sum of oxidation numbers equals the charge on the ion or molecule.

氧化数有助于识别氧化还原过程：单质的氧化数为 0；离子或分子中各原子氧化数的代数和等于其所带电荷。

An electrochemical cell uses spontaneous redox reactions to produce electrical energy. The standard cell potential E°_cell is given by:

原电池利用自发的氧化还原反应产生电能。标准电池电动势 E°_cell 由下式给出：

E°_cell = E°_reduction (cathode) − E°_reduction (anode)

A positive E°_cell indicates the reaction is thermodynamically feasible. The cell with the higher E° value undergoes reduction at the cathode.

E°_cell 为正表示反应热力学可行。具有较高标准电极电势的半电池在阴极发生还原反应。

Oxidising agents gain electrons and are themselves reduced; reducing agents lose electrons and are themselves oxidised.

氧化剂得到电子，自身被还原；还原剂失去电子，自身被氧化。

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11. Reaction Kinetics and the Arrhenius Equation | 反应动力学与阿伦尼乌斯方程

hemical reactions. Rate = change in concentration ÷ time, often expressed as mol dm⁻³ s⁻¹.

动力学研究化学反应速率。速率 = 浓度变化 ÷ 时间，常用 mol dm⁻³ s⁻¹ 表示。

The rate equation links rate to reactant concentrations: Rate = k[A]^m[B]ⁿ, where k is the rate constant, m + n is the overall order.

速率方程关联速率与反应物浓度：Rate = k[A]^m[B]ⁿ，其中 k 为速率常数，m + n 为总反应级数。

The Arrhenius equation explains how temperature affects the rate constant:

阿伦尼乌斯方程解释了温度如何影响速率常数：

k = Ae^−Eₐ/(RT)

tial factor, Eₐ = activation energy (J mol⁻¹), R = 8.314 J K⁻¹ mol⁻¹, T = temperature (K).

A = 指前因子，Eₐ = 活化能 (J mol⁻¹)，R = 8.314 J K⁻¹ mol⁻¹，T = 温度 (K)。

used: ln k = ln A − Eₐ/(RT). A plot of ln k vs 1/T gives a straight line with slope −Eₐ/R.

常用线性形式：ln k = ln A − Eₐ/(RT)。以 ln k 对 1/T 作图得到一条直线，斜率为 −Eₐ/R。

eory requires proper orientation and sufficient energy (E ≥ Eₐ) for successful collisions.

碰撞理论要求分子以合适的取向和足够的能量 (E ≥ Eₐ) 才能发生有效碰撞。

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12. Organic Functional Groups and Isomerism | 有机官能团与异构现象

Organic chemistry is organised by functional groups. The key ones for SQA Higher are listed below.

有机化学按官能团分类，以下为 SQA 高等化学需要掌握的关键官能团。

Homologous series	Functional group	Suffix/prefix
Alkane	C−C (single bonds only)	-ane
Alkene	C=C	-ene
Alcohol	−OH	-ol
Carboxylic acid	−COOH	-oic acid
Ester	−COO−	alkyl -oate
Aldehyde	−CHO	-al
Ketone	C=O (between C atoms)	-one
Amine	−NH₂	amino- / -amine

Isomerism: structural isomers have the same molecular formula but different structural arrangements (chain, position, functional group). Stereoisomers have the same structural formula but differ in spatial arrangement (E/Z (geometric) isomers and optical isomers).

异构现象：构造异构体分子式相同但原子连接方式不同（碳架异构、位置异构、官能团异构）。立体异构体构造相同，但原子空间排列不同（E/Z (几何) 异构和旋光异构）。

two different substituents on each carbon is required; priority is determined by the Cahn–Ingold– irality) arises when a carbon atom has four different groups attached (asymmetric centre).

E/Z 异构要求 C=C 双键，每个碳上连有两个不同的取代基；优先级由 Cahn–Ingold–Prelog 规则确定。旋光异构（手性）产生于一个碳原子连接四个不同基团时（不对称中心）。

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