Complete Chemistry for Cambridge Secondary Workbook: Experimental Skills | 《剑桥中学化学完整练习册：实验操作技能》

📚 Complete Chemistry for Cambridge Secondary Workbook: Experimental Skills | 《剑桥中学化学完整练习册：实验操作技能》

Practical work is at the heart of chemistry. In the Cambridge Secondary 1 and IGCSE curriculum, learning how to perform experiments safely and accurately is just as important as understanding theory. This article covers the essential experimental techniques found in the Complete Chemistry for Cambridge Secondary Workbook, helping students build confidence in the laboratory and succeed in their practical assessments.

实验操作是化学的核心。在剑桥中学及IGCSE课程中，学习如何安全、准确地进行实验与理解理论同样重要。本文涵盖了《剑桥中学化学完整练习册》中的关键实验技术，帮助学生建立实验室信心并在实践考核中取得成功。

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1. Safety in the Laboratory | 实验室安全

Always wear safety goggles, a lab coat, and closed-toe shoes. Long hair must be tied back, and loose clothing secured.

始终佩戴护目镜、实验服和不露趾鞋。长发必须束起，宽松衣物应固定好。

Read the label on reagent bottles twice – before removing and before using – to avoid mistakes. Never return unused chemicals to their original containers.

取用试剂前和使用前都要阅读标签，以防出错。未用完的化学品绝不可倒回原瓶。

When heating, point the mouth of a test tube away from yourself and others. Use a blue Bunsen flame for strong heating and a yellow flame for gentle warming or as a safety flame when not in use.

加热时，试管口要朝向无人处。用本生灯的蓝色火焰进行强热，黄色火焰用于温和加热，不用时则用安全火焰。

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2. Measuring Mass and Volume | 测量质量和体积

Use an electronic balance on a level surface. Tare the balance before placing chemicals, or measure the mass by difference. Record masses to the nearest 0.01 g where possible.

将电子天平放在水平面上。称量前归零，或采用差量法称量。记录质量时尽可能精确到 0.01 g。

For volumes, use the appropriate apparatus: a graduated cylinder for approximate volumes, a volumetric flask for standard solutions, a pipette (with filler) for fixed volumes, and a burette for variable deliveries, especially in titrations. Always read the bottom of the meniscus at eye level.

量取体积时选用合适仪器：量筒用于粗略体积，容量瓶配制标准溶液，移液管（搭配洗耳球）量取固定体积，滴定管用于可变体积的加入，特别在滴定中。读数时视线要与凹液面底部持平。

Check that apparatus is clean and free from cracks. A dirty pipette or burette can deliver inaccurate volumes.

检查仪器是否洁净、无破损。不洁的移液管或滴定管会导致体积不准。

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3. Heating Techniques | 加热技术

Direct heating of a test tube should be done gently by moving the tube in and out of the flame, starting at the top of the liquid and moving downwards. Use a test tube holder.

直接加热试管时应轻轻移动试管进出火焰，从液面顶端开始逐渐向下加热。使用试管夹。

For heating beakers or flasks, always use a wire gauze, tripod, and heatproof mat. Never heat a closed container. When boiling a liquid, add anti-bumping granules to prevent sudden boiling.

加热烧杯或烧瓶时，务必使用铁丝网、三脚架和隔热垫。不得加热密闭容器。沸腾液体时加入沸石防止暴沸。

In a water bath, indirect heating is achieved by placing the container in a beaker of water, which is then heated. This is suitable for flammable liquids or when gentle, even heating is required.

水浴加热是将容器放入装有水的烧杯中再加热，以实现间接加热。适用于易燃液体或需要温和均匀加热的情况。

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4. Filtration and Separation | 过滤与分离

To separate an insoluble solid from a liquid, use filter paper folded into a cone placed in a filter funnel. Pour the mixture down a glass rod to avoid splashing; the solid (residue) stays on the paper and the liquid (filtrate) passes through.

分离不溶性固体与液体时，将滤纸折成圆锥形放入漏斗。用玻璃棒引流倒入混合物，避免飞溅；固体（残渣）留在滤纸上，液体（滤液）穿过。

For a finer separation, fluted filter paper can be used to speed up filtration. Gravity filtration is slow; vacuum filtration using a Büchner funnel and flask can give faster results.

为更精细分离，可用折叠滤纸加速过滤。常压过滤较慢；使用布氏漏斗和抽滤瓶进行抽滤可更快得到结果。

Decantation is carefully pouring off a liquid from a settled solid; it is simple but less efficient.

倾析法是小心地将上层清液倒出，简便但效率较低。

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5. Evaporation and Crystallisation | 蒸发与结晶

To obtain a soluble salt from a solution, gently heat the solution in an evaporating basin until crystals begin to form around the edge (point of crystallisation). Then allow it to cool slowly; large crystals will form. The remaining solution can be decanted, and crystals dried on filter paper.

从溶液中获得可溶性盐时，在蒸发皿中缓慢加热溶液直到边缘出现晶膜（结晶点）。然后让其慢慢冷却，形成大晶体。倾去余液，将晶体放在滤纸上晾干。

Do not evaporate to dryness if you want well-formed crystals; rapid evaporation yields a powder. Slow cooling produces larger, purer crystals.

若想得到形状完好的晶体，不可加热至干；快速蒸发会产生粉末。缓慢冷却可得到更大更纯的晶体。

Recrystallisation is a technique to purify a solid: dissolve in minimum hot solvent, filter hot, cool to crystallise, filter and wash with cold solvent.

重结晶是一种提纯固体的方法：用最少的热溶剂溶解，趁热过滤，冷却结晶，过滤并用冷溶剂洗涤。

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6. Distillation | 蒸馏

Simple distillation is used to separate a solvent from a solution (e.g., pure water from salt water). The solution is heated in a flask; the vapour passes through a condenser where it cools and condenses back into liquid, collected in a receiving vessel.

简单蒸馏用于从溶液中分离溶剂（如从盐水中获得纯水）。在烧瓶中加热溶液，蒸汽通过冷凝管冷凝成液体，收集在接收容器中。

The thermometer bulb must be positioned at the mouth of the condenser or just near the side arm to measure the boiling point of the vapour. Water enters the condenser at the lower end and leaves at the upper end to ensure efficient cooling.

温度计水银球应置于冷凝管口或支管口附近，以测量蒸汽沸点。冷凝水从下端进、上端出，保证冷却效率。

Fractional distillation using a fractionating column is used for miscible liquids with different boiling points (e.g., ethanol and water). The column provides a temperature gradient for repeated condensation and evaporation, improving separation.

使用分馏柱的分馏用于沸点不同的互溶液体（如乙醇和水）。分馏柱提供温度梯度，通过多次冷凝蒸发改善分离效果。

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7. Chromatography | 色谱法

Paper chromatography separates mixtures of soluble substances, such as dyes or pigments. A base line is drawn in pencil, a spot of the mixture applied, and the paper is placed in a solvent with the line above the solvent level. The solvent rises by capillary action, carrying components at different rates.

纸色谱法可分离可溶性混合物，如染料或色素。用铅笔画基线，点上混合物斑点，将纸放入溶剂中，基线高于液面。溶剂因毛细作用上升，以不同速率携带各组分。

Rf value = distance moved by spot / distance moved by solvent front. It is used to identify substances under identical conditions.

Rf值 = 斑点移动距离 / 溶剂前沿移动距离。在相同条件下可用于物质鉴定。

Thin-layer chromatography (TLC) is similar but uses a silica-coated plate, giving better separation. For colourless compounds, use a locating agent or UV light.

薄层色谱（TLC）类似，但使用涂有硅胶的板，分离效果更好。无色化合物可用显色剂或紫外灯显示斑点。

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8. Titration | 滴定

An acid-base titration is used to find the concentration of an unknown solution. A pipette is used to measure a fixed volume (aliquot) of one solution into a conical flask. A few drops of indicator (e.g., phenolphthalein or methyl orange) are added.

酸碱滴定用于测定未知溶液的浓度。用移液管量取一份固定体积的溶液（整份）至锥形瓶中，加入几滴指示剂（如酚酞或甲基橙）。

The burette is filled with the other solution, and the initial reading recorded. The tap is opened to add the solution while swirling the flask until the endpoint is reached (a permanent colour change). Record the final burette reading; the difference is the titre.

滴定管中加入另一种溶液，记录初始读数。打开旋塞滴加溶液，同时摇动锥形瓶，直到达到终点（颜色永久变化）。记录最终读数，差值即为滴定体积。

A rough titration is done first to find the approximate endpoint, followed by accurate titrations to obtain concordant results (within

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