📚 IB Chemistry: A Guide to Experimental Techniques | IB 化学：实验操作指南
Experimental work lies at the heart of IB Chemistry, developing not only practical skills but also an appreciation for the scientific method. From precise titrations to the careful separation of mixtures, every technique demands attention to detail, safety awareness, and robust data analysis. This guide walks you through essential laboratory procedures, highlighting common pitfalls and giving you the confidence to perform with accuracy and insight.
实验操作是 IB 化学的核心，它不仅培养实践技能，还加深了对科学方法的理解。从精确的滴定操作到混合物的细致分离，每一种技术都需要关注细节、注重安全意识和可靠的数据分析。本指南将带你逐一掌握基本的实验室操作流程，重点指出常见误区，让你能够精准、有见地地完成实验。
1. Safety First | 安全第一
Always wear a lab coat and safety goggles from the moment you enter the laboratory. Closed-toe shoes are mandatory, and long hair must be tied back. Know the location of the eyewash station, safety shower, fire extinguisher, and first aid kit before starting any experiment.
从进入实验室的那一刻起，必须始终穿着实验服并佩戴护目镜。必须穿不露趾的鞋，长发要扎在脑后。在开始任何实验之前，务必了解洗眼器、安全淋浴器、灭火器和急救箱的位置。
Work in a fume hood when handling volatile, toxic, or pungent chemicals. Never taste chemicals, and avoid direct inhalation of any vapour. Read the Safety Data Sheet for each substance used, paying particular attention to hazard pictograms and risk phrases.
处理挥发性、有毒或刺激性化学品时，要在通风橱中操作。切勿品尝化学药品，并避免直接吸入任何蒸气。每用一样试剂前都要阅读其安全数据表，尤其注意危险象形图和风险短语。
Dispose of chemical waste in designated containers, never down the sink unless explicitly permitted. Report all spills and breakages immediately to your teacher or lab technician.
将化学废液倒入指定的容器中，除非明确允许，否则绝不能倒入水槽。一旦发生泄漏或玻璃器皿破损，立即报告老师或实验员。
2. Handling of Chemicals and Apparatus | 化学品与仪器使用
Always read the label twice before removing a reagent from the bottle. Use a clean spatula for solids and never return unused chemicals to the original container to avoid contamination. For liquids, pour from the bottle with the label facing your palm to prevent drips damaging the label.
从试剂瓶中取出试剂前，务必两次核对标签。取用固体要用干净的药匙，未用完的化学药品绝不能倒回原瓶以免造成污染。倾倒液体时，要使标签朝向手心，防止液滴损坏标签。
Handle all glassware with care, checking for cracks before heating. Use tongs or heat-resistant gloves for hot apparatus. When assembling apparatus with rubber stoppers, moisten the glass with water or glycerol and twist gently; never force it.
小心对待所有玻璃器皿，在加热前要检查有无裂痕。拿取热仪器要使用坩埚钳或耐热手套。用橡皮塞组装装置时，要用水或甘油润湿玻璃，轻轻旋转插入，切勿用力硬塞。
Rinse pipettes and burettes with the solution they will deliver before use. For weighing, use a level balance on a stable bench; a piece of paper or a weighing boat must be used, and the balance should be tared before each measurement.
移液管和滴定管在使用前必须先用即将盛装的溶液润洗。称量时，需在天平稳定且水平的台面上操作；必须使用称量纸或称量舟，并在每次测量前将天平归零。
3. Measurement and Uncertainty | 测量与不确定度
All measurements carry uncertainty. For analogue instruments such as a thermometer or a burette, the absolute uncertainty is typically half the smallest scale division. For example, a 50 cm³ burette graduated to 0.1 cm³ has an absolute uncertainty of ±0.05 cm³ for a single reading. For digital instruments, the uncertainty is usually the smallest reading displayed.
所有测量都带有不确定度。对于温度计、滴定管等模拟仪器，绝对不确定度通常是其最小刻度值的一半。例如，一支分为 0.1 cm³ 的 50 cm³ 滴定管，单次读数的绝对不确定度为 ±0.05 cm³。对于数字仪器，不确定度通常是所显示的最小读数。
Percentage uncertainty is calculated as:
百分不确定度按下式计算：
Percentage uncertainty = (absolute uncertainty ÷ measured value) × 100%
When a volume is measured as 22.30 cm³ on a burette with ±0.05 cm³ uncertainty, the percentage uncertainty = (0.05 ÷ 22.30) × 100% ≈ 0.22%. Propagate uncertainties for calculations by adding percentage uncertainties for multiplication/division and adding absolute uncertainties for addition/subtraction.
用滴定管测得体积为 22.30 cm³，若不确定度为 ±0.05 cm³，则百分不确定度 = (0.05 ÷ 22.30) × 100% ≈ 0.22%。在计算中，乘除运算要叠加百分不确定度，加减运算则叠加绝对不确定度以传递误差。
4. Titration Techniques | 滴定技术
A titration determines the concentration of an unknown solution by reacting it with a standard solution of known concentration. Rinse the burette with the titrant solution, fill it, and remove any air bubbles from the tip. Record the initial burette reading to the nearest 0.05 cm³. Pipette the aliquot of the unknown into a conical flask using a volumetric pipette, and add a suitable indicator such as phenolphthalein or methyl orange.
滴定是利用已知浓度的标准溶液与未知溶液反应，从而确定未知浓度的方法。先用滴定剂润洗滴定管，加满液体并赶走尖嘴处的气泡。记录初始读数至最接近的 0.05 cm³。用胖肚移液管准确移取一份未知液至锥形瓶中，并加入合适的指示剂，例如酚酞或甲基橙。
Swirl the flask continuously while adding titrant, and slow to dropwise near the endpoint. The endpoint is reached when a permanent colour change occurs with just one drop. Repeat the titration until concordant results are obtained — typically three values within 0.10 cm³ of each other. Then calculate the mean titre from these concordant readings.
滴定过程中不断摇动锥形瓶，接近终点时逐滴加入。当多加入一滴便出现持久色变时即为终点。重复滴定至获得吻合结果为止——通常需三次滴定液体积之差在 0.10 cm³ 以内。然后用这些吻合数据计算平均滴定体积。
5. Using a Burette and Pipette | 滴定管与移液管的使用
Both burettes and pipettes deliver precise volumes, but they must be used correctly. For a burette, ensure it is clamped vertically and read the meniscus at eye level, using the bottom of the concave meniscus. A burette card (a white card with a dark stripe) can help reduce parallax error.
滴定管和移液管都能提供精准体积，但必须正确使用。滴定管要垂直夹稳，视线与凹液面最低点齐平读数。使用滴定管卡片（白底黑条的卡片）有助于减少视差。
When using a volumetric pipette, never pipette by mouth; always use a pipette filler or bulb. Rinse the pipette with the solution, then draw liquid to a little above the graduation mark. Wipe the outside, adjust the meniscus precisely to the mark, and allow the liquid to drain freely into the flask. Touch the tip to the inner wall for about 3 seconds after draining; do not blow out the last drop unless the pipette is specified as ‘blow‑out’.
使用胖肚移液管时，严禁用嘴吸液；必须使用洗耳球或移液器辅助。先用待取溶液润洗移液管，然后吸取液体至略高于刻度线。擦拭外壁，准确将弯月面调至刻度，再让液体自然流下。排空后使管尖接触容器内壁约 3 秒；除非移液管标注“需吹出”，否则不要吹出最后残留液滴。
6. Heating Methods | 加热方法
Different experiments require different heating approaches. A Bunsen burner provides intense direct heat and is used for heating in open vessels, but never heat flammable solvents with it. Use a water bath for gentle, uniform heating up to 100 °C, ideal for evaporating solutions or warming reactions safely.
不同实验需要不同的加热方式。本生灯可提供强烈的直接加热，适合敞口容器加热，但绝不可用它加热易燃溶剂。水浴可提供最高 100 °C 的温和均匀加热，是蒸发溶液或安全加热反应的理想选择。
Heating under reflux is essential when carrying out reactions that produce volatile substances. The vertical condenser returns evaporated solvent to the flask, preventing loss and ensuring complete reaction. A heating mantle provides even heat for round-bottom flasks and avoids hot spots that could cause bumping.
当反应涉及挥发性物质时，回流加热必不可少。竖直安放的冷凝管能将蒸发的溶剂送回烧瓶，避免损失并确保反应完全。加热套为圆底烧瓶提供均匀加热，避免局部过热导致的暴沸。
7. Filtration and Crystallization | 过滤与结晶
Gravity filtration uses filter paper folded in a funnel to separate an insoluble solid from a liquid. Flute the filter paper or use the quadrant fold to increase surface area. For faster, more efficient separation, use vacuum filtration with a Buchner funnel and side-arm flask; ensure the filter paper covers all holes and is wetted before starting.
重力过滤利用漏斗中折叠的滤纸分离不溶性固体和液体。可将滤纸折成褶扇形或四折式以增加过滤面积。若要实现更快、更高效的分离，可使用布氏漏斗和抽滤瓶进行减压过滤；确保滤纸覆盖所有小孔并在使用前润湿。
For crystallization, dissolve the crude product in a minimum volume of hot solvent, filter if necessary, and allow the solution to cool slowly. Slow cooling promotes the formation of larger, purer crystals. Collect crystals by vacuum filtration, wash with a little cold solvent, and dry them between filter papers or in a desiccator.
结晶时，将粗产物溶于尽可能少的热溶剂中，必要时过滤，然后让溶液缓慢冷却。缓慢冷却有利于生成较大且纯度更高的晶体。用减压过滤收集晶体，以少量冷溶剂洗涤，再在滤纸间或干燥器中干燥。
8. Chromatography | 色谱法
Paper chromatography and thin-layer chromatography (TLC) are used to separate and identify components of a mixture. Mark the baseline with pencil, never pen, as ink would run. Apply tiny spots of sample using a capillary tube, dry them, and repeat to build concentration without enlarging the spot too much.
纸色谱和薄层色谱（TLC）用于分离和鉴定混合物组成。基线必须用铅笔标记，绝不能用墨水笔，因墨水会扩散。用毛细管点上微量样品点，吹干后重复点样以增加浓度，但注意不要让斑点扩张过大。
Place the plate in a developing chamber with a small depth of solvent, ensuring spots are above the solvent level. Allow the solvent to rise to about 1 cm from the top, then remove and mark the solvent front immediately. Calculate Rf values (distance moved by spot ÷ distance moved by solvent front) and compare with standards.
将薄板放入盛有少量展开剂的展开缸中，确保斑点高于液面。让展开剂上行至距顶端约 1 cm 处，取出并立即标记溶剂前沿。计算 Rf 值（斑点移动距离 ÷ 溶剂前沿移动距离），并与标准品对照。
9. pH Measurement and Electrochemistry | pH 测量与电化学
Universal indicator paper provides a quick estimate of pH, but for precise measurements use a pH meter. Calibrate the pH meter with buffer solutions of known pH (e.g. pH 4.00 and pH 7.00) before use. Rinse the electrode with distilled water and gently blot dry between measurements.
广泛 pH 试纸能快速估计 pH 值，但精密测量要使用 pH 计。使用前先用已知 pH 的缓冲溶液（如 pH 4.00 和 pH 7.00）校准 pH 计。每次测量间用蒸馏水冲洗电极，并用滤纸轻轻吸干。
In electrochemistry, half-cell potentials are measured relative to a standard hydrogen electrode (SHE). The cell potential E°cell is found from E°(cathode) − E°(anode) under standard conditions. A salt bridge, often a strip of filter paper soaked in KNO₃, completes the circuit by allowing ion migration without direct mixing of half-cell solutions.
在电化学中，半电池电势是相对于标准氢电极 (SHE) 测量的。标准条件下，电池电动势 E°cell = E°(阴极) − E°(阳极)。盐桥（常为浸泡过 KNO₃ 溶液的滤纸条）让离子迁移而防止半电池溶液直接混合，从而构成完整回路。
10. Data Recording and Error Analysis | 数据记录与误差分析
Record data immediately in a well-organised lab notebook, using tables with clear headings and units. Include estimated uncertainties for every measurement. Graphs should be drawn with labelled axes, suitable scales, and error bars if uncertainties are known. Use a line of best fit to highlight trends, and describe any outliers explicitly.
立即将数据记录在条理清晰的实验笔记本上，使用带有明确标题和单位的表格。每次测量都应注明预估的不确定度。作图时要标明坐标轴并选择合适的刻度；若知道不确定度，还要画出误差棒。用最佳拟合线显示趋势，并明确描述所有离群值。
Differentiate between systematic errors (e.g. uncalibrated burette, clock running slow) and random errors (e.g. judgement in reading a meniscus). Systematic errors affect accuracy and can often be reduced by better calibration. Random errors affect precision and are minimised by taking repeat measurements and averaging.
要区分系统误差（如未校准的滴定管、走时变慢的时钟）和随机误差（如读取弯月面时的判断）。系统误差影响准确度，通常可通过更好的校准来减小。随机误差影响精密度，通过重复测量并取平均值可以最大程度地降低其影响。
11. Common Pitfalls and Troubleshooting | 常见错误与故障排除
In titrations, overshooting the endpoint is a frequent mistake; if it happens, record the new reading but exclude the trial from concordant results. Using too much indicator can shift the endpoint pH, so add only 2–3 drops. Air bubbles in the burette tip lead to falsely high titre values, so always purge them before starting.
滴定中最常见的错误是冲过终点；万一发生，记录此时读数，但把这次滴定从吻合数据中剔除。指示剂加入过多会改变终点 pH，因此最多加 2–3 滴。滴定管尖嘴内藏有气泡会使滴定液体积读数虚高，所以使用前务必将气泡排净。
During filtration, slow drainage may be due to clogged pores; try using a coarser filter or applying gentle suction. Low yield in crystallisation often results from cooling too quickly or using too much solvent; always cool slowly and scratch the flask side to induce nucleation if needed.
过滤速度慢可能是因为滤孔堵塞，可尝试使用更粗的滤纸或轻微减压。结晶产率低往往是由冷却过快或溶剂过量导致的；务必缓慢冷却，必要时可用玻璃棒刮擦瓶壁诱导晶核形成。
Poor TLC separation can occur if the spot is too large or the developing chamber is not saturated. Place a piece of filter paper inside the chamber to saturate the atmosphere with solvent vapour.
TLC 分离效果不佳可能是因为点样太大或展开缸未达到饱和。可以在展开缸内壁贴一张滤纸，使溶剂蒸气充分饱和。
12. IA-Specific Tips | 专题建议——为 IA 加分
Your Internal Assessment (IA) is an opportunity to demonstrate personal engagement and rigorous methodology. Choose a research question that allows you to manipulate a variable and collect quantitative data. The rationale must be clearly linked to chemical concepts, and the procedure should be detailed enough for another student to replicate.
内部评估（IA）是你展示个人投入和严谨方法的绝佳机会。选择一个能让你操纵变量并收集定量数据的研究问题。研究依据必须与化学概念明确关联，实验步骤要足够详尽，以便其他同学能够重复。
When recording data, show all raw data with associated uncertainties. Use graphs to determine derived quantities (e.g. rate constant from a slope). Evaluation must critically discuss method limitations, distinguish between random and systematic errors, and propose realistic improvements. A strong IA shows genuine curiosity and clear, scientific reflection.
记录数据时，应显示所有原始数据及其不确定度。利用作图确定导出量（如从斜率求速率常数）。评估部分必须批判性地讨论方法局限性，区分随机误差和系统误差，并提出切实可行的改进方案。一份优秀的 IA 会体现出真正的好奇心和清晰的科学反思。
Published by TutorHao | Chemistry Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
屏轩国际教育cambridge primary/secondary checkpoint, cat4, ukiset,ukcat,igcse,alevel,PAT,STEP,MAT, ibdp,ap,ssat,sat,sat2课程辅导，国外大学本科硕士研究生博士课程论文辅导Cancel reply