📚 Year 10 OCR Chemistry: Formula & Theorem Quick Reference Handbook | Year 10 OCR 化学：公式定理速查手册
This handy reference guide brings together the essential formulas, equations, and key concepts you need for Year 10 OCR Chemistry. From moles and molar mass to bonding and electrolysis, each section explains the core principles in plain English and Chinese, with clear equations you can rely on during revision. Use it as a quick check before exams or to reinforce classroom learning.
这本速查手册汇集了 Year 10 OCR 化学所需的核心公式、方程式和关键概念。从摩尔、摩尔质量到化学键和电解，每个部分用清晰的中英双语解释基本原理，并列出可靠的方程，便于复习时快速查阅，也可用来巩固课堂所学。
1. Relative Atomic Mass and Relative Formula Mass | 相对原子质量与相对式量
The relative atomic mass (Ar) is the average mass of an atom of an element compared to 1/12 the mass of a carbon-12 atom. It has no units. The relative formula mass (Mr) is the sum of the Ar values of all atoms in a chemical formula.
相对原子质量 (Ar) 是某元素一个原子的平均质量与碳-12 原子质量的 1/12 的比值，没有单位。相对式量 (Mr) 是化学式中所有原子的 Ar 之和。
Mr = Σ Ar (of each atom in the formula)
For example, water H2O: Mr = 2×1 + 16 = 18. For magnesium hydroxide Mg(OH)2: Mr = 24 + 2×(16+1) = 58. Remember brackets multiply everything inside.
例如，水 H2O：Mr = 2×1 + 16 = 18。氢氧化镁 Mg(OH)2：Mr = 24 + 2×(16+1) = 58。注意括号会将内部原子数翻倍。
2. The Mole and Molar Mass | 摩尔与摩尔质量
A mole is the amount of substance that contains 6.02 × 10²³ particles (Avogadro' ole, measured in grams per mole (g/mol). Numerically, M equals the relative formula mass Mr.
一摩尔是包含 6.02 × 10²³ 个微粒（阿伏伽德罗常数）的物质的量。某物质的摩尔质量 (M) 是一摩尔该物质的质量，单位是克每摩尔 (g/mol)。M 的数值等于相对式量 Mr。
n = m ÷ M
Here n is the number of moles, m is the mass in grams, and M is the molar mass in g/mol. Always convert mass to grams before using this formula.
式中 n 是摩尔数，m 是质量（克），M 是摩尔质量（g/mol）。使用此公式前务必先将质量换算成克。
3. Moles in Solutions: Concentration | 溶液中的摩尔：浓度
The concentration of a solution tells us how much solute is dissolved in a given volume. Concentration (c) is measured in mol/dm³. 1 dm³ equals 1000 cm³.
溶液的浓度表示在一定体积中溶解了多少溶质。浓度 (c) 的单位是 mol/dm³。1 dm³ 等于 1000 cm³。
n = c × V (where V is in dm³)
dm³ by dividing by 1000. For example, 250 cm³ = 0.250 dm³. The formula becomes n = c × (Vcm³ / 1000).
如果体积单位是 cm³，需除以 1000 转换为 dm³。例如 250 cm³ = 0.250 dm³。公式变为 n = c × (Vcm³ / 1000)。
4. Moles of Gases: Molar Volume | 气体摩尔：摩尔体积
At room temperature and pressure (RTP), one mole of any gas occupies a volume of 24 dm³. This is the molar gas volume. The same relationship can be expressed with 24 000 cm³.
在室温和常压下 (RTP)，一摩尔任何气体占据 24 dm³ 的体积。这就是摩尔气体体积。同样的关系也可以用 24 000 cm³ 表示。
n = Vgas ÷ 24 (V in dm³ at RTP)
Or if using cm³: n = Vgas ÷ 24 000. This only applies to gases, not solids or liquids. Temperature and pressure must be stated.
或者用 cm³ 计算：n = V气体 ÷ 24 000。该公式仅适用于气体，不适用于固体或液体，且需注明温度和压强条件。
5. Chemical Equations and Stoichiometry | 化学方程式与化学计量
A balanced chemical equation shows the ratio of moles of reactants and products. Coefficients in front of formulas indicate the number of moles. Stoichiometry uses these mole ratios to calculate masses, volumes or concentrations.
配平的化学方程式体现反应物与生成物之间的摩尔比。化学式前的系数代表摩尔数。化学计量利用这些摩尔比来计算质量、体积或浓度。
For the reaction: 2H2 + O2 → 2H2O, the mole ratio is 2:1:2. If 4 moles of H2 react, 2 moles of O2 are needed and 4 moles of H2O form.
对于反应 2H2 + O2 → 2H2O，摩尔比为 2:1:2。若 4 摩尔 H2 反应，需要 2 摩尔 O2，生成 4 摩尔 H2O。
Steps for mass calculations: oles → use mole ratio → convert moles back to mass. Always start with a balanced equation.
质量计算步骤：将质量换算成摩尔 → 利用摩尔比 → 再将摩尔换算回质量。务必从配平的方程式开始。
6. Conservation of Mass | 质量守恒定律
In a chemical reaction, the total mass of reactants equals the total mass of products. Atoms are neither created nor destroyed; they are only rearranged. This is why we balance equations.
在化学反应中，反应物的总质量等于生成物的总质量。原子既不会被创造也不会被消灭，只是重新排列。因此我们需要配平方程式。
Apparent mass changes can occur if a gas is released or absorbed from the air. For a closed system, total mass stays constant.
如果反应中释放出气体或从空气中吸收气体，可能会出现表观质量变化。在封闭系统中，总质量保持不变。
7. Ionic and Covalent Bonding Rules | 离子键与共价键规则
Ionic bonding occurs between metals and non-metals. Electrons are transferred from the metal to the non-metal, forming positive and negative ions. The total charge in an ionic compound must be zero.
离子键发生在金属与非金属之间。电子从金属转移到非金属，形成阳离子和阴离子。离子化合物的总电荷必须为零。
Covalent bonding happens between non-metals. Atoms share pairs of electrons to achieve a full outer shell. The number of bonds an atom typically forms equals the number of electrons it needs to reach a noble gas configuration.
共价键发生在非金属之间。原子通过共享电子对来达到满外电子层。一个原子通常形成的键数等于其达到稀有气体构型所需电子数。
For ionic formulas, e.g. Mg²⁺ + 2Cl⁻ → MgCl2
Use 'cross-over' method: swap the ion charges to get the ratio, then simplify. For aluminium oxide, Al³⁺ and O²⁻ give Al2O3.
使用“交叉”法：交换离子电荷得到比例，再化简。氧化铝：Al³⁺ 与 O²⁻ 得到 Al2O3。
8. Acids, Bases and pH | 酸、碱与pH
An acid is a substance that releases H⁺ ions in aqueous solution. A base is a substance that can neutralise an acid, often releasing OH⁻ ions. pH scale measures acidity: 0-6 acidic, 7 neutral, 8-14 alkaline.
酸是在水溶液中释放 H⁺ 离子的物质。碱是可以中和酸的物质，通常释放 OH⁻ 离子。pH 标度衡量酸碱度：0~6 酸性，7 中性，8~14 碱性。
H⁺(aq) + OH⁻(aq) → H2O(l)
This is the ionic equation for neutralisation. When an acid and a base react, they produce a salt and water. The name of the salt comes from the acid and the metal in the base.
这是中和反应的离子方程式。酸与碱反应生成盐和水。盐的名称来源于所用的酸和碱中的金属。
Titration formula: nacid = cacidVacid, nbase = cbaseVbase. At the endpoint, the mole ratio from the balanced equation is used to find the unknown.
滴定公式：n酸 = c酸V酸，n碱 = c碱V碱。在终点时，利用平衡方程式中的摩尔比求出未知量。
9. Electrolysis Principles | 电解原理
Electrolysis is the breakdown of an ionic compound using direct current. It requires an electrolyte (molten or dissolved ionic compound) and two electrodes. Cations move to the cathode (−) and are reduced; anions move to the anode (+) and are oxidised.
电解是利用直流电分解离子化合物。需要电解质（熔融或溶解的离子化合物）和两个电极。阳离子移向阴极 (−) 被还原；阴离子移向阳极 (+) 被氧化。
In aqueous solutions, the products depend on the reactivity of the metal and the presence of water. At the cathode, if the metal is more reactive than hydrogen, H2 gas forms; otherwise the metal forms. At the anode, oxygen forms from OH⁻ unless a halide ion is present.
在水溶液中，产物取决于金属的活泼性和水的存在。在阴极，若金属比氢活泼，则生成 H2；否则析出金属。在阳极，除非存在卤素离子，否则由 OH⁻ 产生氧气。
Half equations show electron transfer. Example at cathode: Cu²⁺ + 2e⁻ → Cu. At anode: 2Cl⁻ → Cl2 + 2e⁻.
半反应方程式表示电子转移。例如阴极：Cu²⁺ + 2e⁻ → Cu。阳极：2Cl⁻ → Cl2 + 2e⁻。
10. Energy Changes: Exothermic and Endothermic | 能量变化：放热与吸热
Exothermic reactions release energy to the surroundings, causing a temperature rise. Endothermic reactions absorb energy from the surroundings, causing a temperature drop. Bond breaking is endothermic; bond making is exothermic.
放热反应向周围释放能量，导致温度升高。吸热反应从周围吸收能量，导致温度降低。断裂化学键吸热；形成化学键放热。
ΔH = energy of bonds broken – energy of bonds formed
ΔH < 0 for exothermic reactions, ΔH > 0 for endothermic. Energy diagrams show activation energy and overall enthalpy change.
放热反应 ΔH < 0，吸热反应 ΔH > 0。能量图显示活化能和总焓变。
11. Percentage Yield and Atom Economy | 产率与原子经济性
Percentage yield compares the actual mass of product to the maximum theoretical mass. It is never 100% due to incomplete reactions, side reactions or product lost during purification.
产率将实际得到的产物质量与最大理论质量进行比较。由于反应不完全、副反应或纯化过程中的损失，产率通常达不到 100%。
% yield = (actual mass ÷ theoretical mass) × 100
Atom economy measures the efficiency of a reaction in terms of atoms used to form the desired product. Higher atom economy means less waste.
原子经济性衡量反应中用于生成目标产物的原子效率。原子经济性越高，废物越少。
% atom economy = (Mr of desired product ÷ sum of Mr of all reactants) × 100
12. Reactivity Series and Displacement | 金属活动性顺序与置换反应
The reactivity series lists metals in order of their tendency to lose electrons and form positive ions. A more reactive metal can displace a less reactive metal from its compound.
金属活动性顺序按金属失去电子形成阳离子的倾向排列。较活泼的金属能把较不活泼的金属从其化合物中置换出来。
For example, zinc displaces copper from copper(II) sulfate solution: Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s). The blue colour fades as copper metal forms.
例如锌能从硫酸铜溶液中置换出铜：Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)。随着铜的生成，蓝色逐渐褪去。
Unreactive metals like gold and silver can be found native, while reactive metals like potassium are extracted by electrolysis.
像金和银这种不活泼金属可以以单质形式存在，而像钾这样的活泼金属则通过电解提取。
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