IGCSE OCR Chemistry: Practical Skills Guide | IGCSE OCR 化学：实验操作指南

📚 IGCSE OCR Chemistry: Practical Skills Guide | IGCSE OCR 化学：实验操作指南

This guide covers essential practical skills required for IGCSE OCR Chemistry, including safety, measurement, separation techniques, titration, and gas handling. Mastery of these techniques is vital for both the written examination and the practical assessment.

本指南涵盖IGCSE OCR化学所需的关键实验操作技能，包括安全、测量、分离技术、滴定和气体操作等。掌握这些技术对于笔试和实践评估都至关重要。

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1. Safety in the Chemistry Laboratory | 化学实验室安全

Always wear safety goggles and a lab coat to protect your eyes and clothing from chemical splashes. Tie back long hair and avoid loose clothing.

始终佩戴护目镜和实验服，保护眼睛和衣物免受化学品飞溅。将长发束起，避免穿着宽松的衣服。

When smelling a chemical, waft the vapour towards your nose with your hand; never place the container directly under your nostrils.

闻化学药品时，用手将蒸气扇向鼻子；切勿将容器直接放在鼻孔下闻。

Report all breakages and spillages immediately to your teacher. Dispose of broken glass in the designated sharps bin, not in the ordinary waste bin.

所有破损和溢洒立即报告老师。碎玻璃应放入指定的锐器桶，不要丢入普通垃圾桶。

Heating should be carried out with care. When heating a test tube, point the open end away from yourself and others. Use a test-tube holder.

加热时要小心。加热试管时，管口应朝向无人的方向，并使用试管夹。

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2. Measuring and Recording | 测量与记录

Use appropriately precise apparatus for measurement: a measuring cylinder for approximate volumes, a pipette or burette for accurate volumes, and a balance for mass.

使用适当精度的仪器进行测量：量筒用于粗略量取体积，移液管或滴定管用于精确量取，天平用于称量质量。

Read the bottom of the meniscus at eye level for colourless liquids in a burette or measuring cylinder. For coloured liquids, read the top of the meniscus.

读取滴定管或量筒中的无色液体时，视线应与弯月面的最低点水平。对于有色液体，则读取弯月面的最高点。

Record all measurements to the appropriate number of decimal places, considering the instrument’s precision. For example, a burette reading should be recorded to ±0.05 cm³, such as 23.45 cm³.

根据仪器精度记录所有测量值到合适的小数位数。例如，滴定管读数应记录至±0.05 cm³，如23.45 cm³。

When using a balance, tare the weighing container before adding the substance. Record the mass to at least 0.01 g for analytical work.

使用天平时，先称量空容器并去皮，再加入药品。分析实验须记录质量至少至0.01 g。

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3. Heating Techniques | 加热技术

Use a Bunsen burner with a blue (non-luminous) flame for strong heating, as it provides the hottest and cleanest flame. Open the air hole fully to obtain the blue flame.

使用本生灯时，应打开空气孔得到蓝色（非发光）火焰进行强热，因为它温度最高且最洁净。

For gentle heating or when flammable solvents are involved, use a water bath or an electric heater. A water bath ensures even heating and prevents temperatures from exceeding 100 °C.

需要温和加热或涉及易燃溶剂时，使用水浴或电加热器。水浴可确保均匀加热，并防止温度超过100 °C。

When heating a solid in a test tube, clamp the tube almost horizontally and heat gently at first, moving the flame along the tube. Avoid directing the flame at one spot to prevent localised overheating.

加热试管中的固体时，将试管略倾斜固定，先缓慢移动火焰加热。避免火焰集中在一个点，以防局部过热。

Never heat a closed container, and always provide an opening for gases to escape. Use boiling chips or anti-bumping granules when heating liquids to prevent bumping.

切勿加热密闭容器，务必留有气体逸出的开口。加热液体时加入沸石或防暴沸颗粒，防止暴沸。

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4. Preparing Solutions | 配制溶液

To prepare a standard solution, accurately weigh the solid solute using a weighing boat and analytical balance. Transfer the solid into a beaker, dissolve in distilled water, and then transfer to a volumetric flask via a funnel, using a glass rod to guide the liquid.

配制标准溶液时，用称量舟和分析天平准确称取固体溶质。将固体转移到烧杯中，用蒸馏水溶解，然后借助玻璃棒引流，通过漏斗转移到容量瓶中。

Rinse the beaker, funnel and stirring rod with distilled water several times and add these washings to the volumetric flask. This ensures all solute is transferred.

用蒸馏水淋洗烧杯、漏斗和玻璃棒数次，并将洗涤液一并转入容量瓶，确保所有溶质都转移。

Add distilled water until the level reaches just below the calibration mark. Use a dropping pipette to add water dropwise until the bottom of the meniscus is exactly on the mark. Stopper and invert the flask several times to mix thoroughly.

加入蒸馏水至刻度线稍下方，然后用滴管逐滴加水，直至弯月面底部与刻度线相切。盖紧瓶塞，上下倒转容量瓶数次，使溶液混合均匀。

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5. Filtration and Evaporation | 过滤与蒸发

Fold filter paper into a cone and place it in a filter funnel. The paper should fit snugly, and its edge should be about 0.5 cm below the rim of the funnel. Wet the paper with distilled water to make it adhere.

将滤纸折叠成圆锥形放入漏斗中，滤纸应紧贴漏斗壁，其边缘应低于漏斗边缘约0.5 cm。用蒸馏水湿润滤纸使其贴紧。

Pour the mixture to be filtered down a glass rod resting against the filter paper, directing the stream onto the triple-thickness side of the paper. Do not overfill the funnel – keep the liquid level below the rim of the filter paper.

将待过滤混合物沿玻璃棒引流到滤纸上，液流应对准滤纸三层叠加的一侧。不要将漏斗装得过满——保持液面低于滤纸边缘。

For evaporation, pour the filtrate into an evaporating basin and heat gently over a Bunsen burner or on a water bath. Stop heating when crystals are just beginning to form or after reducing the volume sufficiently. Then leave to cool for crystallisation.

蒸发时，将滤液倒入蒸发皿，用本生灯或水浴缓缓加热。当溶液开始出现晶体或体积浓缩到合适程度时，停止加热，然后冷却结晶。

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6. Crystallisation | 结晶

After partial evaporation, allow the hot, concentrated solution to cool slowly to room temperature. Crystals will form as the solubility decreases. A seed crystal can be added to induce crystallisation if necessary.

部分蒸发后，让热的浓溶液缓慢冷却至室温。随着溶解度下降，晶体会逐渐析出。如有必要，可加入晶种诱导结晶。

Filter the crystals using a Buchner funnel and suction filtration if large quantities are produced, or simply use a funnel and dry filter paper. Wash the crystals with a little cold distilled water to remove any impurities adhering to the surface, and then dry between sheets of filter paper or in a low-temperature oven.

用布氏漏斗和抽滤获得大量晶体，或简单使用漏斗和干滤纸过滤。用少量冷蒸馏水淋洗晶体，除去表面附着的杂质，然后在滤纸间吸干或低温烘箱中干燥。

Aim for large, well-formed crystals by cooling slowly without disturbance. Rapid cooling produces many small crystals. Record the colour, shape and yield of the purified product.

通过缓慢无干扰冷却可获得大而规则的晶体。快速冷却则生成许多小晶体。记录纯化产品的颜色、晶形和产率。

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7. Simple Distillation | 简单蒸馏

Simple distillation separates a liquid from a dissolved solid or from another liquid with a significantly different boiling point. Assemble a round-bottom flask, a still-head with a thermometer, a Liebig condenser and a receiving flask.

简单蒸馏用于从溶解的固体中分离出液体，或分离沸点差异较大的两种液体。装配圆底烧瓶、带温度计的蒸馏头、直形冷凝管和接收瓶。

The thermometer bulb should be positioned just below the side arm of the still-head to measure the temperature of the vapour. Cooling water must enter the condenser at the lower inlet port and exit from the upper port to ensure efficient cooling.

温度计水银球应位于蒸馏头支管口稍下方，以测量蒸气温度。冷却水必须从冷凝管的下口进入、上口流出，以保证充分冷却。

Heat the flask evenly and gradually. The distillate collected will be the pure liquid with the lower boiling point. Stop heating before the flask runs dry to avoid thermal

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