📚 CH01-INS International Chemistry AS Practical Operation Guide (10 May 2023) | CH01-INS 国际化学 AS 实验操作指南 (2023年5月10日)
The CH01-INS insert for the International Chemistry AS examination on 10 May 2023 outlines the practical tasks and instructions that candidates must follow under timed conditions. This guide breaks down the essential experimental operations, common pitfalls, and data-handling techniques needed to excel in such paper-based practical assessments. Whether you are revisiting titration, calorimetry, or qualitative analysis, understanding the insert’s expectations is as critical as executing the steps flawlessly.
2023年5月10日国际化学AS考试的CH01-INS插页列出了考生必须在限时条件下遵循的实践任务与指令。本指南分解了在此类笔试实验中脱颖而出的关键实验操作、常见易错点以及数据处理技术。无论你是重新练习滴定、量热还是定性分析，理解插页的考察意图与完美执行步骤同等关键。
1. Understanding the Insert Instructions | 理解实验指令
Before handling any apparatus, read the entire CH01-INS insert carefully. It tells you the aim of each part, the reagents provided, and any special precautions such as ‘add the solid in small portions’. Skipping a line like ‘record all temperatures to the nearest 0.1 °C’ can cost you valuable precision marks.
在操作任何仪器之前，请仔细通读整份CH01-INS插页。它会告知你每个部分的目标、提供的试剂以及任何特殊注意事项，例如“少量多次加入固体”。如果忽略诸如“将所有温度记录至最接近的0.1 °C”的要求，很可能会丢掉宝贵的精确度分数。
The insert often includes tables for you to complete. Note which columns require calculated values, such as temperature change (ΔT) or titre volume. Highlight instruction verbs like ‘determine’, ‘calculate’, and ‘explain’, as they indicate what the examiner expects in your written responses.
插页通常包含需要你填写的表格。留意哪些列需要计算值，例如温度变化(ΔT)或滴定体积。圈出“确定”“计算”和“解释”等指令动词，因为它们表明了考官的书面回答预期。
2. Safety Precautions | 安全预防措施
Always wear safety goggles and a lab coat as instructed. The insert may remind you that 2 mol dm⁻³ HCl is corrosive. If a substance is irritant, avoid inhaling its dust or vapour. Wash any spillages immediately with plenty of water and report to the supervisor.
务必按照指令佩戴护目镜和实验服。插页可能会提醒你2 mol dm⁻³ HCl具有腐蚀性。若物质具有刺激性，避免吸入其粉尘或蒸气。任何溢出物应立即用大量水冲洗，并报告监考老师。
For calorimetry experiments, the glass thermometer is fragile; handle it carefully to avoid mercury or alcohol spill. When heating solutions with a spirit burner, keep the flame away from flammable solvents and ensure proper ventilation.
在量热实验中，玻璃温度计易碎；小心操作以避免汞或酒精泄漏。使用酒精灯加热溶液时，请将火焰远离易燃溶剂，并确保适当通风。
3. Accurate Weighing and Volume Measurement | 精确称量与体积测量
Use a top-pan balance recording to the nearest 0.01 g or 0.001 g as specified. Always use a clean, dry weighing boat and press the ‘tare’ button before adding the solid. Record the mass immediately to avoid transcription errors.
使用上皿天平，按照要求记录至最接近的0.01 g或0.001 g。务必使用清洁干燥的称量舟，在加入固体前按下“去皮”键。立即记录质量以避免抄写错误。
For liquid volumes, a volumetric pipette is more accurate than a measuring cylinder. Rinse the pipette with the solution it will contain, and allow it to drain under gravity, touching the tip to the inner wall. Use a 25.0 cm³ pipette with a filler to deliver exactly 25.0 cm³.
就液体体积而言，容量移液管比量筒更精确。用待盛装的溶液润洗移液管，任其在重力作用下排空，将管尖靠触容器内壁。使用25.0 cm³移液管配以洗耳球，准确移取25.0 cm³。
4. Titration Technique and End-point Detection | 滴定技巧与终点判断
Before starting, rinse the burette with the titrant and fill it past the zero mark. Open the tap briefly to remove air bubbles from the jet. Record the initial reading to the nearest 0.05 cm³. A dark background, such as a white tile under the flask, makes colour changes clearer.
开始前，先用滴定剂润洗滴定管并注满至零刻线以上。短暂打开旋塞，排除尖嘴处的气泡。将初始读数记录至最接近的0.05 cm³。深色背景，比如锥形瓶下垫一张白色瓷砖，能使颜色变化更清晰。
Add the titrant slowly, swirling the flask continuously. Approaching the end-point, you should see the colour change linger before disappearing; at this stage, add dropwise or even half-drops. The concordant titres should agree within ±0.10 cm³. Record your final reading, then repeat until you have two or three concordant values.
缓慢加入滴定剂，持续旋摇锥形瓶。接近终点时，应能看到颜色变化先出现再消失；此时需逐滴甚至半滴加入。相符的滴定体积差值应在±0.10 cm³以内。记录终读数，然后重复直至获得两到三个相符的数值。
5. Measuring Enthalpy Change | 焓变测定
In a typical neutralisation calorimetry, measure 25.0 cm³ of the acid into a polystyrene cup. Record the initial temperature of the acid and the base separately to verify they are within 0.5 °C of each other. Note the temperature at 30-second intervals for three minutes, then add the base at the fourth minute exactly.
在典型的中和量热法中，量取25.0 cm³酸液注入聚苯乙烯杯中。分别记录酸和碱的初始温度，验证两者温差在0.5 °C以内。在3分钟内每30秒记录一次温度，然后在第4分钟整时加入碱液。
Continue stirring and recording the temperature every 30 seconds for another 8 minutes. Plot temperature against time, then draw two best-fit straight lines through the data points before and after addition. Extrapolate back to the mixing time to find the maximum temperature change (ΔT) corrected for heat loss.
继续搅拌并每30秒记录一次温度，再持续8分钟。绘制温度-时间图，然后通过添加前后的数据点各画一条最佳拟合直线。外推至混合时刻，即可得到校正热量损失后的最大温度变化(ΔT)。
Q = m c ΔT and ΔH = -Q / n
Use the total volume to estimate the mass (assuming density 1.00 g cm⁻³), specific heat capacity c = 4.18 J g⁻¹ K⁻¹, and the number of moles n from concentration and volume.
使用总体积估算质量（假设密度为1.00 g cm⁻³），比热容c = 4.18 J g⁻¹ K⁻¹，以及由浓度和体积得出的摩尔数n。利用Q = m c ΔT计算热量，再用ΔH = -Q / n计算焓变。
6. Qualitative Analysis: Ion Tests | 定性分析：离子检验
The insert may ask you to identify cations and anions. For flame tests, clean a nichrome wire with concentrated HCl, dip into the sample, and place in a blue Bunsen flame. Na⁺ gives a persistent yellow flame; K⁺ gives lilac (use cobalt glass to filter yellow); Ca²⁺ yields brick-red; Cu²⁺ produces a blue-green flame.
插页可能会要求你鉴别阳离子和阴离子。就焰色反应而言，用浓HCl清洁镍铬丝，蘸取样品后置于蓝色本生灯火焰中。Na⁺产生持续黄色火焰；K⁺呈紫色（用钴玻璃滤掉黄色）；Ca²⁺呈砖红色；Cu²⁺呈蓝绿色。
For anions, add dilute nitric acid followed by a reagent: for Cl⁻, add AgNO₃ to get a white precipitate soluble in dilute NH₃; for SO₄²⁻, add BaCl₂ to obtain a white precipitate insoluble in dilute HCl; for CO₃²⁻, add acid and look for effervescence, test the gas with limewater.
对于阴离子，加入稀硝酸后加入试剂：鉴定Cl⁻时，加入AgNO₃得白色沉淀，可溶于稀NH₃；鉴定SO₄²⁻时，加入BaCl₂得白色沉淀，不溶于稀HCl；鉴定CO₃²⁻时，加酸并观察冒泡，将气体通入石灰水检验。
7. Data Recording and Significant Figures | 数据记录与有效数字
Always record raw data in an organised table. Headings must include the quantity being measured and its unit, e.g., ‘Temperature / °C’. Do not enter calculated values into the raw data section. Use the same level of precision for all readings from the same instrument: a burette reading of 23.40 cm³, not 23.4 cm³.
应始终将原始数据记录在整洁的表格中。表头必须包含被测量的量及其单位，例如“温度 / °C”。不要把计算值填入原始数据栏。同一仪器的所有读数应保持相同的精密度：滴定管读数应为23.40 cm³，而非23.4 cm³。
When calculating molarities or enthalpy, match the significant figures to the least precise measurement. For instance, if mass is given to 3 significant figures and volume to 4, your final concentration should be expressed to 3 significant figures, e.g., 0.104 mol dm⁻³.
计算摩尔浓度或焓变时，有效数字应与最不精确的测量值匹配。例如，若质量精确到3位有效数字，体积精确到4位，则最终浓度应表示为3位有效数字，如0.104 mol dm⁻³。
8. Errors and Uncertainties | 误差与不确定度
Systematic errors, such as a balance that reads +0.02 g when empty, affect accuracy and can be eliminated by taring or calibration. Random errors, like reading a thermometer by different amounts each time, affect precision and are reduced by taking multiple readings.
系统误差（例如天平在空载时读数为+0.02 g）影响准确度，可通过去皮或校准来消除。随机误差（例如每次读取温度计时的量差）影响精密度，可通过多次读数来减小。
Calculate the percentage uncertainty for a burette: (0.05 cm³ × 2) / mean titre × 100%. If using a 25 cm³ pipette with tolerance ±0.06 cm³, the percentage uncertainty is 0.06 / 25 × 100% = 0.24%. Compare these with the percentage difference between your replicate titres to assess reliability.
计算滴定管的百分不确定度：(0.05 cm³ × 2) / 平均滴定体积 × 100%。如使用25 cm³移液管，允差±0.06 cm³，则百分不确定度为0.06 / 25 × 100% = 0.24%。将这些与重复滴定间的百分差异对比，以评估可靠性。
9. Graph Plotting and Calculations | 绘图与计算
For a thermometric titration or cooling curve, use a sharp pencil and labeled axes with units. Draw a line of best fit that passes as close to as many points as possible, ignoring obvious outliers. Use the extrapolation method to find the corrected temperature change without heat loss distortion.
绘制温度滴定曲线或冷却曲线时，用削尖的铅笔和带单位的标记坐标轴。画一条最佳拟合线，使其尽可能靠近最多数据点，忽略明显异常值。用外推法求出校正后的温度变化，以消除热量损失带来的失真。
When determining the concentration of an unknown via titration, use the concordant titre volume. Apply the formula c₁V₁/n₁ = c₂V₂/n₂, where n₁ and n₂ are the stoichiometric coefficients. For HCl + NaOH → NaCl + H₂O, the ratio is 1:1, so cacid × Vacid = cbase × Vbase.
通过滴定确定未知物浓度时，使用相符的滴定体积。应用公式c₁V₁/n₁ = c₂V₂/n₂，其中n₁和n₂是化学计量系数。对于HCl + NaOH → NaCl + H₂O，比例为1:1，因此c酸 × V酸 = c碱 × V碱。
10. Common Operational Mistakes | 常见操作错误
Air bubbles in the burette jet will increase the measured titre and lead to inconsistent results. Always flush the jet before initial reading. Using a wet conical flask for titration does not change the moles of the aliquot, but water in the pipette or burette will dilute the solution and alter concentrations.
滴定管尖嘴中的气泡会增大所测滴定体积，导致结果不一致。务必在读取初始值前排空尖嘴。使用潮湿的锥形瓶进行滴定不会改变移取部分的物质的量，但移液管或滴定管中的水会稀释溶液并改变浓度。
During calorimetry, failing to stir the mixture continuously or losing the thermometer to touch the cup’s wall gives erratic temperatures. Starting the stopwatch late or early can misalign the mixing time, corrupting the extrapolated ΔT. Always practice the timing sequence beforehand.
在量热实验中，未能持续搅拌混合物或温度计触碰杯壁会导致温度读数异常。提前或滞后启动秒表会错配混合时刻，破坏外推的ΔT。务必事先演练计时流程。
11. Marking Criteria and Report Writing | 评分标准与报告写作
In AS practical papers, marks are awarded for correct recording, clear table headings, appropriate significant figures, and concordant results. You are expected to comment on the reliability of your data and suggest realistic improvements, such as ‘use a lid on the polystyrene cup to reduce heat loss’.
在AS实验卷中，正确记录、清晰表头、适当有效数字以及相符结果都能得分。你需评述数据的可靠性并提出切实可行的改进建议，例如“给聚苯乙烯杯加上盖子以减少热量损失”。
When writing conclusions, refer back to the purpose stated in the insert. Compare your calculated value with a known data book value, if given, and assess the sources of error. Use the phrase ‘the major source of error is… because…’ to show analytical thinking.
撰写结论时，应回扣插页中说明的目的。将计算值与已知数据手册值（若提供）比较，并评估误差来源。使用“主要误差来源是……因为……”的句式，以展示分析性思维。
12. Mock Practice and Exam Day Tips | 模拟演练与应考提示
Simulate the CH01-INS task under strict time control, ideally 45–60 minutes per major experiment. Print a blank insert and practise filling in the tables, plotting graphs, and answering follow-up questions. This builds speed and reveals whether you tend to misread instructions.
在严格的时间控制下模拟CH01-INS任务，理想情况下每个主要实验用时45–60分钟。打印空白插页，练习填表、绘图及回答后续问题。这能提高速度，也可发现你是否容易误读指令。
On exam day, check that all reagents and apparatus match the insert description before beginning. If a solid appears crystallised in the reagent bottle, gently shake it before use, but never return unused chemicals to stock bottles. Stay calm; the practical paper tests your ability to follow a procedure, not your dexterity alone.
考试当天，开始前先检查所有试剂和仪器是否与插页描述吻合。假如试剂瓶内固体出现结晶，可轻轻摇匀后使用，但切勿将未用完的化学品倒回储存瓶。保持冷静；实验卷考查的是你遵循流程的能力，而不仅仅是动手操作的灵巧。
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