GCSE OCR Chemistry: Formula Summary Handbook | GCSE OCR 化学：公式汇总手册

📚 GCSE OCR Chemistry: Formula Summary Handbook | GCSE OCR 化学：公式汇总手册

Mastering the key chemical calculations is essential for success in GCSE OCR Chemistry. This handbook compiles all the important formulas you need for quantitative chemistry, energy changes, rates, and analytical techniques. Use it as a quick reference for revision and exam practice.

掌握关键化学计算对于 GCSE OCR 化学的成功至关重要。本手册汇总了定量化学、能量变化、速率和分析技术所需的所有重要公式。可将其用作复习和考试练习的快速参考。

1. The Mole and Molar Mass | 摩尔与摩尔质量

The mole (mol) is the SI unit for amount of substance. The relationship between mass, molar mass, and number of moles is given by:

n = m / M

摩尔（mol）是物质的量的国际单位。质量、摩尔质量和摩尔数之间的关系由下式给出：n = m / M，其中 n 为摩尔数，m 为质量（g），M 为摩尔质量（g/mol）。

2. Concentration of Solutions | 溶液浓度

The concentration of a solution in mol/dm³ (M) can be calculated using the number of moles and the volume of the solution:

c = n / V

溶液的浓度以 mol/dm³ (M) 为单位可通过摩尔数和溶液体积计算：c = n / V，其中 c 为浓度（mol/dm³），n 为溶质的摩尔数，V 为溶液体积（dm³）。注意 1 dm³ = 1000 cm³。

3. Gas Volumes at RTP | 室温下气体体积

At room temperature and pressure (RTP), one mole of any gas occupies a volume of 24 dm³ (or 24,000 cm³). The volume of a gas can be found from its number of moles:

V (dm³) = n × 24

在室温常压下，1 摩尔任何气体占据 24 dm³（或 24000 cm³）的体积。气体的体积可从其摩尔数求得：V (dm³) = n × 24。若以 cm³ 为单位，则 V (cm³) = n × 24000。

4. Percentage Yield | 产率

Percentage yield compares the actual mass of product obtained to the theoretical maximum mass predicted from the balanced equation:

% Yield = (actual yield / theoretical yield) × 100

产率将实际得到的产品质量与根据配平方程式预测的理论最大质量进行比较：% 产率 = (实际产量 / 理论产量) × 100。

5. Atom Economy | 原子经济性

Atom economy measures the efficiency of a reaction in incorporating reactant atoms into the desired product. It is calculated using relative formula masses (Mr):

% Atom Economy = (Mr of desired product / sum of Mr of all reactants) × 100

原子经济性衡量反应物原子进入目标产物的效率。它使用相对式量 (Mr) 计算：% 原子经济性 = (目标产物的 Mr / 所有反应物的 Mr 之和) × 100。注意：方程式中反应物的系数必须乘以其 Mr。

6. Energy Changes – Calorimetry | 能量变化–量热法

The heat energy transferred in a reaction can be determined by measuring a temperature change in a known mass of water (or solution) using the equation:

q = m c ΔT

反应中传递的热能可通过测量已知质量水（或溶液）的温度变化来确定，使用公式：q = m c ΔT，其中 q 为热量（J），m 为质量（g），c 为比热容（水的比热容为 4.2 J/g/°C），ΔT 为温度变化（°C）。

To find the molar enthalpy change (ΔH), divide the heat energy by the number of moles and add the appropriate sign (negative for exothermic, positive for endothermic):

ΔH = –q / n

要求摩尔焓变（ΔH），将热量除以摩尔数并加上合适的符号（放热为负，吸热为正）：ΔH = –q / n（单位 J/mol 或 kJ/mol）。通常需将 J 转换为 kJ（除以 1000）。

7. Rate of Reaction | 反应速率

The average rate of a reaction can be expressed as the change in amount of a reactant or product per unit time. Common quantities measured include mass loss or volume of gas produced:

Rate = change in quantity / time

平均反应速率可表示为反应物或产物的量的变化除以时间。常用的测量量包括质量损失或产生的气体体积：速率 = 量的变化 / 时间。单位可为 g/s、cm³/s 等。

8. Percentage Composition by Mass | 质量百分比组成

To find the mass percentage of an element in a compound, use the relative atomic mass (Ar) and the relative formula mass (Mr):

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GCSE OCR Chemistry: Formula Summary Handbook | GCSE OCR 化学：公式汇总手册