Complete Chemistry Laboratory Techniques | 化学实验操作技术大全

📚 Complete Chemistry Laboratory Techniques | 化学实验操作技术大全

Mastering laboratory techniques is a cornerstone of success in chemistry. From accurate measurement and safe heating to precise titration and effective separation, every skill builds the foundation for reliable experimentation and deeper understanding of chemical principles.

掌握实验操作技术是化学学习成功的基石。从精确的测量和安全的加热，到精准的滴定和高效的分离，每一项技能都为可靠的实验操作和对化学原理的深入理解打下坚实基础。

1. Laboratory Safety and Rules | 实验室安全与基本规则

Always wear safety goggles and a lab coat to protect against splashes. Tie back long hair and avoid loose clothing. Never eat, drink, or taste chemicals in the lab.

务必佩戴护目镜和实验服以防止液体飞溅。长发要束起，避免穿着宽松衣物。实验室内绝对禁止饮食或尝试任何化学品。

Know the location of safety equipment such as the eyewash station, fire extinguisher, and first aid kit. In case of skin contact with corrosive chemicals, rinse immediately with plenty of water for at least 15 minutes.

了解安全设备的位置，如洗眼器、灭火器和急救箱。如果皮肤接触到腐蚀性化学品，应立即用大量清水冲洗至少15分钟。

Work in a well-ventilated area or a fume cupboard when handling volatile or toxic substances. Always read labels and hazard symbols before using any reagent.

在处理挥发性或有毒物质时，要在通风良好的区域或通风橱内操作。使用任何试剂前，务必阅读标签和危险符号。

Dispose of chemical waste according to the instructor’s guidelines. Never return unused chemicals to the original bottle to avoid contamination.

根据教师指导处理化学废弃物。切勿将未用完的化学品倒回原瓶，以免污染。

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2. Basic Glassware and Equipment | 基础玻璃仪器与器材

A beaker is used for holding, mixing, and heating liquids but is not suitable for accurate volume measurements. An Erlenmeyer flask has a narrow neck, ideal for swirling without spillage and for titrations.

烧杯用于盛放、混合和加热液体，但不适合精确的体积测量。锥形瓶瓶颈较细，适合旋摇液体而不会溅出，常用于滴定操作。

A graduated cylinder provides a more precise volume measurement than a beaker, but for volumetric analysis a volumetric flask or bulb pipette must be used because they are calibrated to deliver a fixed volume with high accuracy.

量筒比烧杯提供更精确的体积测量，但在容量分析中必须使用容量瓶或移液管，因为它们经过校准，能够以高准确度提供固定体积。

A Bunsen burner supplies a flame for heating; its air hole adjusts the flame from yellow (safety flame) to blue (roaring flame). A tripod and wire gauze support the glassware evenly.

本生灯提供加热用的火焰；其气孔可调节火焰从黄色（安全焰）到蓝色（强焰）。三脚架和铁丝网用于均匀支撑玻璃仪器。

Test tubes are used for small-scale reactions, and a test tube holder prevents burns when heating. A spatula is used to transfer solid chemicals, and a dropper pipette transfers small amounts of liquids.

试管用于小规模反应，试管夹可在加热时防止烫伤。药匙用于转移固体化学品，滴管用于转移少量液体。

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3. Heating Techniques | 加热操作技术

When heating a liquid in a test tube, point the mouth away from yourself and others. Heat the tube gently at the surface of the liquid, moving constantly to avoid bumping.

在试管中加热液体时，管口要朝向无人处。轻轻地加热液体表面，不断移动试管以防暴沸。

Use a water bath for flammable organic solvents or for reactions requiring gentle, uniform heat below 100 °C. An oil bath or heating mantle is preferred for temperatures above 100 °C.

对于易燃有机溶剂或需要在低于100°C均匀温和加热的反应，使用水浴。温度超过100°C时，则宜使用油浴或加热套。

Avoid direct flame contact with glassware that is not borosilicate (e.g., Pyrex); it may crack. Always use a wire gauze or ceramic-centered mat to diffuse heat.

避免使不耐热的非硼硅玻璃（如普通玻璃）直接接触火焰，否则可能破裂。始终使用铁丝网或陶瓷网垫来扩散热量。

When boiling a liquid, add anti-bumping granules before heating to ensure smooth boiling and prevent vigorous eruption.

加热煮沸液体前，需加入沸石，以保证沸腾平稳并防止剧烈喷溅。

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4. Measuring Volume: Graduated Cylinder and Pipette | 体积测量：量筒与移液管

Place the graduated cylinder on a level surface and read the bottom of the meniscus at eye level. Estimate to one-tenth of the smallest scale division.

将量筒放在水平面上，视线与弯月面最低处平齐进行读数。估读至最小刻度的十分之一。

A volumetric pipette delivers a single fixed volume, e.g., 25.0 cm³. Rinse the pipette with the solution to be transferred, then fill it above the mark using a pipette filler, not your mouth.

移液管可准确转移单一固定体积，如25.0 cm³。先用待移取溶液润洗移液管，然后用洗耳球吸取液体至标线以上，严禁用嘴吸。

After filling, wipe the outside of the tip with tissue, then slowly allow the liquid to drain until the meniscus touches the calibration mark. Touch off the tip to the inner wall of the receiving vessel.

吸满液体后，用纸巾擦干管尖外壁，然后缓慢放出液体直至弯月面与刻度线相切。将管尖触及接收容器内壁以移出挂余液滴。

For a burette, rinse with the titrant, fill the tip with no air bubbles, and record the initial reading to ±0.05 cm³. Always read the bottom of the meniscus.

对于滴定管，先用滴定剂润洗，确保管尖无气泡，记录初始读数至±0.05 cm³。始终读取弯月面底部。

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5. Weighing and Analytical Balance | 称量与分析天平

Use a top-pan balance for coarse mass measurements, often to 0.01 g or 0.1 g precision. For quantitative analysis, an analytical balance giving 0.001 g or 0.0001 g is necessary.

托盘天平用于粗略称量，精度通常为0.01 g或0.1 g。定量分析需使用精度为0.001 g或0.0001 g的分析天平。

Always place a weighing boat or paper on the pan to protect it, and zero (tare) the balance before adding the sample. Close the draft shield on analytical balances to avoid air currents.

始终在秤盘上放置称量舟或称量纸以保护天平，并在加样前进行去皮（归零）。使用分析天平时应关闭防风罩以防气流干扰。

When weighing hygroscopic substances, use a stoppered weighing bottle. Record the mass by weighing the bottle with substance, then after transferring the required amount.

称量吸湿性物质时使用带塞称量瓶。先称量瓶与物质总质量，转移所需量后再称一次，通过差值计算。

Avoid vibration and temperature fluctuations near the balance. Allow warm objects to cool to room temperature before placing them on the pan.

避免天平附近有振动和温度波动。加热后的物体需冷却至室温后再放到秤盘上。

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6. Separation Techniques: Filtration and Evaporation | 分离技术：过滤与蒸发

Gravity filtration uses a filter paper folded into a cone and placed in a funnel. This method separates an insoluble solid from a liquid. Flute the paper for faster filtration.

常压过滤使用滤纸折叠成锥形置于漏斗中。此法用于分离不溶性固体与液体。将滤纸折成扇形可加快过滤速度。

In vacuum filtration, a Buchner funnel, filter paper, and side-arm flask connected to a water pump draw the liquid through rapidly, ensuring a dry solid residue.

减压过滤利用布氏漏斗、滤纸和抽滤瓶，连接水泵后快速吸滤液，得到较干燥的固体残余物。

Evaporation to dryness is used to obtain a soluble solid from a solution. Heat the evaporating dish gently on a steam bath to avoid spitting and thermal decomposition.

蒸干法用于从溶液中获得可溶性固体。在蒸发皿中温和加热，最好使用水浴，以防迸溅和热分解。

Crystallization is preferable for purifying solids: cool a hot saturated solution slowly to obtain large, pure crystals. Filter, wash with a little cold solvent, and dry between filter papers.

重结晶更适宜纯化固体：将热饱和溶液缓慢冷却以获得大而纯净的晶体。过滤后用少量冷溶剂洗涤，然后在滤纸间吸干。

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7. Distillation and Reflux | 蒸馏与回流

Simple distillation separates a liquid from a non-volatile solute or separates liquids with a boiling point difference greater than about 40 °C. The thermometer bulb must be aligned with the side arm of the distillation flask.

简单蒸馏用于分离液体和不挥发性溶质，或分离沸点差大于约40°C的混合液体。温度计水银球需与蒸馏烧瓶支管口平齐。

Fractional distillation uses a fractionating column packed with glass beads, providing a large surface area for repeated condensation and vaporization. It separates miscible liquids with closer boiling points, e.g., ethanol–water mixture.

分馏使用填有玻璃珠的分馏柱，提供大量表面以进行反复冷凝和汽化，可分离沸点较接近的混溶液体，如乙醇与水的混合物。

Reflux involves heating a reaction mixture to boiling and condensing the vapor back into the flask with a vertical condenser. This technique allows reactions to occur at the solvent’s boiling point without loss of volatile reactants.

回流是将反应混合物加热沸腾，并通过竖直冷凝管将蒸气冷凝回流至烧瓶中。该技术使反应能在溶剂沸点进行而不会损失挥发性反应物。

Always add boiling chips, connect water tubes correctly (water in at the lower jacket), and never stopper a heated closed system.

始终加入沸石，正确连接冷凝水（下口进水），切勿将加热的密闭系统盖紧。

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8. Titration Technique | 滴定操作技术

Rinse the burette with deionized water and then with the titrant. Fill it, ensuring no air bubble remains in the tip. Record the initial burette reading.

先用去离子水再用滴定剂润洗滴定管。装液至无气泡残留于管尖，记录滴定管初读数。

Using a pipette, transfer an accurate volume of analyte to a clean Erlenmeyer flask and add a few drops of a suitable indicator. Swirl constantly during titration.

用移液管准确量取一定体积的被测溶液至洁净锥形瓶中，加入几滴合适的指示剂。滴定过程中不断旋摇锥形瓶。

Add titrant from the burette slowly, switching to dropwise near the endpoint. The endpoint is reached when a permanent colour change appears (e.g., pink of phenolphthalein just persists for 30 seconds).

从滴定管中缓慢加入滴定剂，接近终点时改为逐滴加入。当指示剂产生永久性颜色变化（如酚酞的淡粉色持续30秒）时即为终点。

Record the final burette reading. Repeat titrations until concordant results (within 0.10 cm³) are obtained. Use washed and rinsed apparatus for each trial.

记录滴定管终读数。重复滴定直至获得吻合结果（相差在0.10 cm³以内）。每次试验均使用洗涤并润洗过的仪器。

Calculate the mean titre from concordant values, excluding any rough or outlier readings. The mean titre is used to determine the unknown concentration.

由吻合的滴定值计算平均滴定体积，舍去初试滴定值或离群值。用平均滴定体积计算未知浓度。

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9. Gas Preparation and Collection | 气体制备与收集

Gases are often prepared by the reaction of a solid with a liquid in a side-arm test tube or a gas generator. A delivery tube directs the gas into the collection vessel.

气体常通过固体与液体在支管试管或气体发生器中反应来制备。导气管将气体导入收集容器。

Gases lighter than air (e.g., H₂, NH₃) are collected by upward delivery or by holding an inverted flask. Gases heavier than air (e.g., CO₂, Cl₂) are collected by downward delivery into an upright flask.

比空气轻的气体（如H₂、NH₃）采用向上排空气法或用倒置集气瓶收集。比空气重的气体（如CO₂、Cl₂）采用向下排空气法收集于正立集气瓶中。

Gases that are only slightly soluble in water (e.g., O₂, H₂, CO₂ if not too long contact) are collected over water in a pneumatic trough. This allows easy visualization of the gas volume.

难溶于水的气体（如O₂、H₂、接触时间不长的CO₂）可用排水集气法在水槽中收集。此法便于观察气体体积。

Drying gases: pass the gas through a drying agent such as concentrated H₂SO₄ (for acidic gases), anhydrous CaCl₂, or silica gel in a U-tube or drying tower. The drying agent must not react with the gas.

气体干燥：将气体通过干燥剂，如U型管或干燥塔中的浓H₂SO₄（用于酸性气体）、无水CaCl₂或硅胶。干燥剂不得与气体反应。

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10. Flame Test and Qualitative Analysis | 焰色试验与定性分析

A flame test identifies metal ions based on characteristic colours when a sample is introduced into a Bunsen burner’s blue flame. Use a clean nichrome or platinum wire dipped in concentrated HCl and then into the sample.

焰色试验通过将样品引入本生灯蓝色火焰中产生的特征颜色来识别金属离子。使用洁净的镍铬丝或铂丝先蘸取浓盐酸，再蘸取样品。

Li⁺ gives a red flame, Na⁺ an intense yellow, K⁺ a lilac (viewed through cobalt glass to mask sodium yellow), Ca²⁺ a brick red, and Cu²⁺ a blue-green.

锂离子Li⁺呈红色，钠离子Na⁺呈强烈黄色，钾离子K⁺呈淡紫色（可通过钴玻璃滤去钠黄光），钙离子Ca²⁺呈砖红色，铜离子Cu²⁺呈蓝绿色。

For anion tests, add dilute nitric acid followed by specific reagents: silver nitrate solution to test for halide ions (white ppt for Cl⁻, cream for Br⁻, yellow for I⁻). Sulfate ions give a white precipitate with barium chloride solution acidified with HCl.

阴离子检验时，先加稀硝酸再加特殊试剂：硝酸银溶液检验卤离子（Cl⁻白色沉淀，Br⁻淡黄色，I⁻黄色）。硫酸根离子与用盐酸酸化的氯化钡溶液反应生成白色沉淀。

Carbonate ions produce effervescence with dilute acid; the released CO₂ can be tested with limewater turning milky. Ammonium ions release NH₃ gas when warmed with NaOH, turning damp red litmus blue.

碳酸根离子遇稀酸产生气泡；释放的CO₂使石灰水变浑浊。铵根离子与NaOH加热时释放NH₃气体，使湿润的红色石蕊试纸变蓝。

Always observe the order of tests: eliminate interfering ions first, and use fresh portions for each confirmatory analysis.

严格遵循检验顺序：先排除干扰离子，并对每次确认性分析使用新的试样。

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