📚 SQA National 5 Chemistry Quick-Reference Formula & Theorem Handbook | SQA National 5 化学公式定理速查手册
Mastering key formulas and theorems is the foundation for success in the SQA National 5 Chemistry exam. This handbook summarises all the essential calculations and relationships you need to memorise and apply with confidence. Each section pairs a clear explanation with the corresponding formula, enabling quick revision and error-free application in tests.
掌握核心公式与定理是 SQA National 5 化学考试成功的基础。本手册汇总了所有必须熟记并能灵活运用的重要计算与关系式。每一节将清晰的概念解释与对应的公式配对呈现，助你高效复习并在考试中准确应用。
1. Relative Atomic Mass (RAM) & Formula Mass | 相对原子质量与化学式量
The Relative Atomic Mass (RAM) is the average mass of one atom of an element compared to 1/12th of the mass of a carbon-12 atom. It has no units. The Relative Formula Mass (RFM) is the sum of the RAM values of all atoms in a chemical formula. For ionic compounds we use RFM; for covalent molecules we often refer to Relative Molecular Mass (RMM).
相对原子质量 (RAM) 是元素一个原子的平均质量与一个碳‑12 原子质量的 1/12 的比值，没有单位。相对化学式量 (RFM) 是化学式中所有原子的 RAM 值之和。对于离子化合物我们使用 RFM，对于共价分子我们也常用相对分子质量 (RMM) 这一术语。
RFM = Σ(RAM × number of atoms)
Example: H₂O has RFM = (2 × 1) + 16 = 18. CaCO₃: RFM = 40 + 12 + (3 × 16) = 100.
示例：H₂O 的 RFM = (2 × 1) + 16 = 18。CaCO₃ 的 RFM = 40 + 12 + (3 × 16) = 100。
2. The Mole and Molar Mass | 摩尔与摩尔质量
e Avogadro constant). The molar mass (M) is the mass of one mole of a substance, expressed in g mol⁻¹. Numerically, M equals the RFM or RAM.
1 摩尔是包含 6.02 × 10²³ 个粒子（阿伏伽德罗常数）的物质的量。摩尔质量 (M) 是 1 摩尔物质的质量，单位为 g mol⁻¹，数值上等于 RFM 或 RAM。
The core equation linking mass, amount and molar mass is:
联系质量、物质的量与摩尔质量的核心公式为：
n = m ÷ M
tance (mol), m = mass (g), M = molar mass (g mol⁻¹). Rearrangements: m = n × M; M = m ÷ n.
其中 n 为物质的量 (mol)，m 为质量 (g)，M 为摩尔质量 (g mol⁻¹)。变形公式：m = n × M；M = m ÷ n。
3. Concentration and Volume | 浓度与体积
t to mol L⁻¹). All volumes must be converted to dm³ before calculation (1 dm³ = 1000 cm³).
浓度 (c) 是单位体积溶液中溶解的溶质的物质的量，标准单位为 mol dm⁻³（等同于 mol L⁻¹）。所有体积在计算前必须换算为 dm³ (1 dm³ = 1000 cm³)。
The concentration equation is:
浓度公式为：
c = n ÷ V
nce n = c × V. When diluting a solution, the amount of solute stays the same: c₁V₁ = c₂V₂.
其中 n 为物质的量 (mol)，V 为体积 (dm³)，因此 n = c × V。稀释溶液时溶质的量保持不变，即 c₁V₁ = c₂V₂。
4. Molar Volume of Gases | 气体摩尔体积
At room temperature and pressure (RTP), one mole of any gas occupies the same volume: 24.0 dm³. This value is called the molar volume.
在室温常压 (RTP) 下，1 摩尔任何气体所占的体积相同，均为 24.0 dm³，这一数值称为气体摩尔体积。
n = V(gas) ÷ 24.0
s volume directly to moles, and can be combined with n = m ÷ M to link gas volume to mass.
V(gas) 必须以 dm³ 为单位。该公式直接将气体体积与物质的量关联，并能与 n = m ÷ M 联用，从而联系气体体积与质量。
5. Percentage Composition by Mass | 质量百分比组成
To find the mass percentage of an element in a compound, multiply the total RAM of that element in one formula unit by the number of atoms, divide by the RFM, and multiply by 100%.
计算化合物中某元素的质量百分比时，用该元素在一个化学式单元中的总 RAM（原子个数 × RAM）除以 RFM，再乘以 100%。
% by mass = (total mass of element in 1 mole
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