📚 IB AQA Chemistry: Experimental Operation Guide | IB AQA化学：实验操作指南
Mastering experimental techniques is the cornerstone of success in both IB Chemistry and AQA A-level Chemistry. This comprehensive guide brings together the essential practical skills required for internal assessments, practical examinations, and the development of scientific thinking.
掌握实验技术是在IB化学和AQA A-level化学中取得成功的基石。本综合指南汇集了内部评估、实验考试以及科学思维培养所需的基本实践技能。
1. Laboratory Safety and Good Practice | 实验室安全与良好操作规范
Always wear appropriate personal protective equipment including safety goggles, lab coat, and gloves when handling chemicals or heating substances.
在处理化学试剂或加热物质时，务必佩戴适当的个人防护装备，包括护目镜、实验服和手套。
Know the locations of the eyewash station, safety shower, fire extinguisher, and first-aid kit before starting any experiment.
开始任何实验之前，要熟悉洗眼器、紧急喷淋装置、灭火器和急救箱的位置。
Dispose of chemical waste according to the lab protocol. Never pour organic solvents or heavy-metal solutions down the sink.
根据实验室规程处理化学废弃物。切勿将有机溶剂或含重金属的溶液倒入水槽。
Keep the workspace tidy, and never eat, drink, or chew gum in the laboratory. Tie back long hair and secure loose clothing.
保持工作区整洁，绝不在实验室饮食或嚼口香糖。绑好长发并固定宽松衣物。
2. Measuring Mass Accurately | 准确测量质量
Use an analytical balance capable of reading to ±0.001 g (±1 mg) for quantitative work. For very precise work, a balance with ±0.0001 g (±0.1 mg) may be required.
定量工作中使用精度为 ±0.001 g (±1 mg) 的分析天平。若需要极高精度，可使用 ±0.0001 g (±0.1 mg) 的天平。
Always tare the balance with a weighing boat or paper before adding the substance. Weigh by difference when transferring solids to avoid loss.
在加入物质前，务必用称量舟或称量纸将天平去皮。转移固体时采用差减法称量，避免损失。
Record the mass using the full resolution displayed on the balance, for example 2.305 g rather than 2.3 g.
记录质量时保留天平显示的全部分辨率，例如记录 2.305 g 而非 2.3 g。
Hot or warm objects should be cooled to room temperature in a desiccator before weighing to prevent convection currents affecting the reading.
热的或有余温的物体应先在干燥器中冷却至室温再称量，以防止对流影响读数。
3. Measuring Volume with Precision | 精密测量体积
Select the appropriate glassware based on the required accuracy. Volumetric flasks, burettes, and volumetric pipettes provide Class A or Class B tolerances.
根据所需的准确度选择合适的玻璃器具。容量瓶、滴定管和移液管提供A级或B级公差。
Read the bottom of the meniscus at eye level for transparent solutions. For dark liquids such as KMnO₄, read the top of the meniscus against the graduation line.
透明溶液应在视线水平处读取弯月面底部。对于像 KMnO₄ 这样的深色液体，则以弯月面顶部对准刻度线读取。
A volumetric pipette (e.g. 25.0 cm³) delivers its nominal volume when the tip is touched against the wall of the receiving vessel after free drainage. Do not blow out the last drop.
移液管（如 25.0 cm³）在自由流完后将尖端接触接收容器内壁，即可转移其标称体积。切勿吹出最后一滴。
A burette (50.0 cm³, ±0.05 cm³ tolerance) should be rinsed with the solution to be used, then filled without air bubbles below the tap. Record the initial reading to ±0.05 cm³.
滴定管（50.0 cm³，公差 ±0.05 cm³）应用待用溶液润洗，然后充满，确保旋塞下方无气泡。记录初始读数至 ±0.05 cm³。
4. Titration Technique | 滴定技术
Rinse the burette with the titrant (the solution of known concentration) twice. Fill the burette slightly above the 0.00 cm³ mark, run some solution through the tip to remove air bubbles, then set the initial reading.
用滴定剂（已知浓度的溶液）润洗滴定管两次。将滴定管液面加至 0.00 cm³ 刻度稍上方，放出部分溶液以排尽管尖气泡，然后设置初始读数。
Using a volumetric pipette, transfer a precise aliquot (e.g. 25.0 cm³) of the analyte into a clean conical flask. Add a few drops of a suitable indicator.
用移液管准确量取一份待测溶液（如 25.0 cm³）置于洁净的锥形瓶中，加入几滴合适的指示剂。
During the titration, swirl the flask with one hand while controlling the burette tap with the other. Add the titrant dropwise near the end point until the indicator colour changes permanently.
滴定过程中，一手旋转锥形瓶，另一手控制滴定管旋塞。接近终点时逐滴加入滴定剂，直到指示剂颜色永久改变。
Record the final burette reading to the nearest 0.05 cm³. Obtain concordant titres that agree within 0.10 cm³ of each other. Use the mean of concordant results in calculations.
记录终读数至 0.05 cm³。获得彼此相差不超过 0.10 cm³ 的一致性结果。计算时使用一致性结果的平均值。
| Trial | Rough titre (cm³) | 1st accurate (cm³) | 2nd accurate (cm³) | 3rd accurate (cm³) |
|---|---|---|---|---|
| Final reading | – | 24.35 | 24.45 | 24.40 |
| Initial reading | – | 0.00 | 0.10 | 0.05 |
| Titre volume | (24.2) | 24.35 | 24.35 | 24.35 |
| Concordant results used: mean titre = 24.35 cm³ (24.35, 24.35, 24.35). Ignore rough trial. | ||||
5. Preparing a Standard Solution | 配制标准溶液
A standard solution is prepared by dissolving an accurately known mass of a primary standard in deionised water and making up to an exact volume in a volumetric flask.
标准溶液通过将准确称量的一级标准物质溶于去离子水中，并在容量瓶中定容至精确体积来配制。
Weigh the required mass, calculated from the desired concentration and volume, using an analytical balance. Record the mass to the full balance resolution.
根据所需浓度和体积计算所需质量，用分析天平称量。记录质量时保留天平的全部分辨率。
Transfer all the solid into a clean beaker with rinsings. Add about 50 cm³ of deionised water and stir with a glass rod until completely dissolved.
将全部固体转移至洁净烧杯中，并用淋洗水冲洗称量容器。加入约 50 cm³ 去离子水，用玻璃棒搅拌直至完全溶解。
Transfer the solution to a volumetric flask (e.g. 250.0 cm³) via a funnel. Rinse the beaker, rod, and funnel several times and add the washings to the flask. Make up to the mark with deionised water.
通过漏斗将溶液转移至容量瓶（如 250.0 cm³）中。淋洗烧杯、玻璃棒和漏斗数次，将洗液全部转入容量瓶。用去离子水定容至刻度线。
Stopper the flask, invert it, and shake thoroughly to ensure homogeneity. Label with solute, concentration, date, and your name.
塞好瓶塞，倒转并充分振荡使溶液均匀。贴上标签，注明溶质、浓度、日期和姓名。
6. Heating Methods and Temperature Control | 加热方法与温度控制
Use a Bunsen burner with a blue flame for rapid heating of non-flammable solutions. A tripod and gauze should support the vessel, and the hottest part of the flame should be applied.
如需快速加热不易燃溶液，可使用本生灯的蓝色火焰。用三脚架和石棉网支撑容器，并使火焰的最热部位加热。
A hot-water bath heated on a hotplate is suitable for heating flammable liquids or maintaining a steady temperature below 100 °C. It provides gentle, even heat.
热水浴放在电热板上加热，适用于加热易燃液体或维持 100 °C 以下的稳定温度，可提供温和均匀的加热。
For temperature-sensitive experiments such as enthalpy determinations, use a polystyrene cup as a calorimeter with a lid and stirrer. Record the temperature every 30 seconds, paying attention to the linear drift before and after the reaction.
对于温度敏感的测定如焓变实验，使用带盖和搅拌棒的泡沫聚苯乙烯杯作为量热计。每 30 秒记录一次温度，注意反应前后温度线的线性漂移。
When refluxing, set up a Quickfit apparatus with a vertical condenser, secure the flask with a clamp, and add anti-bumping granules. The water must flow in at the bottom of the jacket and out at the top.
回流操作时，安装带直形冷凝管的Quickfit装置，用夹子固定烧瓶，加入防沸沸石。冷却水必须从冷凝管外套的下端进入、上端流出。
For distillations, mount the thermometer with the bulb opposite the side arm of the still-head. Adjust the heating rate so that distillate drips at a steady rate.
蒸馏时，将温度计的球部对准蒸馏头支管的位置。调节加热速率，使馏出液稳定滴出。
7. Separation Techniques | 分离技术
Gravity filtration uses fluted filter paper in a funnel to separate an insoluble solid from a liquid. The mixture is poured down a glass rod to direct it to the centre of the paper.
重力过滤使用菊花形滤纸和漏斗分离不溶性固体与液体。将混合物沿玻璃棒倾倒在滤纸中央。
Vacuum filtration through a Buchner funnel and suction flask is faster and produces a drier solid. The filter paper must be flattened and wetted before applying suction.
使用布氏漏斗和吸滤瓶的减压过滤更快，并得到更干的固体。在抽吸前，滤纸必须铺平并用溶剂湿润。
Simple distillation is used to separate a liquid from a dissolved solid or liquids with boiling-point differences > 50 °C. Fractional distillation uses a fractionating column to separate liquids with closer boiling points.
简单蒸馏用于分离液体与溶解的固体或沸点差大于 50 °C 的液体。分馏则通过分馏柱分离沸点更接近的液体。
In paper chromatography, a pencil line is drawn about 2 cm from the bottom edge. The sample spot is applied, and the paper is suspended in a solvent. The Rf value is calculated: Rf = distance moved by component / distance moved by solvent front.
在纸色谱法中，用铅笔在距底边约 2 cm 处画线。点上样品点，将滤纸悬于溶剂中。Rf 值计算公式：Rf = 组分移动距离 / 溶剂前沿移动距离。
Thin‑layer chromatography (TLC) uses a silica or alumina plate. Components are often viewed under UV light or developed with iodine vapour after the run.
薄层色谱法 (TLC) 使用硅胶或氧化铝板。运行后，组分通常在紫外灯下观察或用碘蒸气显色。
8. Qualitative Analysis: Ion Tests | 定性分析：离子检验
Flame tests are used to identify metal ions. Clean a nichrome wire loop with concentrated HCl, dip in the sample, and hold in a roaring blue flame. Characteristic colours: Li⁺ carmine red, Na⁺ intense yellow, K⁺ lilac, Ca²⁺ brick red, Ba²⁺ apple green, Cu²⁺ blue-green.
焰色试验用于鉴别金属离子。用浓 HCl 清洁镍铬丝环，蘸取样品，置于旺盛的蓝色火焰中。特征颜色：Li⁺ 胭脂红，Na⁺ 浓黄色，K⁺ 淡紫色，Ca²⁺ 砖红色，Ba²⁺ 苹果绿，Cu²⁺ 蓝绿色。
To test for halides (Cl⁻, Br⁻, I⁻), acidify the solution with dilute HNO₃ and add a few drops of AgNO₃ solution. Observe precipitate colour and test solubility in ammonia.
检验卤离子 (Cl⁻, Br⁻, I⁻) 时，用稀 HNO₃ 酸化溶液，滴加几滴 AgNO₃ 溶液。观察沉淀颜色及在氨水中的溶解性。
| Halide | AgNO₃ precipitate | Dilute NH₃ | Concentrated NH₃ |
|---|---|---|---|
| Cl⁻ | White AgCl | Dissolves | Dissolves |
| Br⁻ | Cream AgBr | Insoluble | Dissolves slowly |
| I⁻ | Yellow AgI | Insoluble | Insoluble |
To identify sulfate ions SO₄²⁻, add dilute HCl followed by BaCl₂ solution. A white precipitate of BaSO₄ confirms sulfate. Carbonate CO₃²⁻ produces effervescence with dilute acid, and the gas turns limewater milky.
检验硫酸根离子 SO₄²⁻ 时，先加稀 HCl 再加 BaCl₂ 溶液，产生白色 BaSO₄ 沉淀即确认存在。碳酸根 CO₃²⁻ 遇稀酸产生气泡，气体使石灰水变浑浊。
9. Enthalpy Change Experiments | 焓变实验
For a neutralisation or displacement reaction, measure a known volume of the first reagent into the calorimeter. Record its temperature every 30 s for 3–4 minutes.
对于中和或置换反应，量取已知体积的第一种试剂置于量热计中。每隔 30 秒记录其温度，持续 3–4 分钟。
At a recorded time, quickly add the second reagent, restart the clock, and continue recording the temperature with constant stirring.
在记录的时间点，迅速加入第二种试剂，重新开始计时，并在持续搅拌下继续记录温度。
Plot temperature against time. Extrapolate the cooling and heating portions to the time of mixing to find the maximum temperature change ΔT at the instant of reaction.
以温度对时间作图。将反应前后冷却和升温部分外推至混合时刻，求得瞬间反应的最大温度变化 ΔT。
q = m × c × ΔT
Calculate the heat energy q absorbed or released using the mass of solution m, specific heat capacity c (usually 4.18 J g⁻¹ K⁻¹ for dilute aqueous solutions), and the corrected ΔT.
利用溶液质量 m、比热容 c（稀水溶液通常取 4.18 J g⁻¹ K⁻¹）和校正后的 ΔT，计算吸收或放出的热量 q。
ΔH = –q / n
The enthalpy change per mole ΔH is obtained by dividing –q by the number of moles n of the limiting reactant. Express ΔH in kJ mol⁻¹.
每摩尔焓变 ΔH 等于 –q 除以限制反应物的物质的量 n，单位为 kJ mol⁻¹。
10. Spectrophotometry and Colorimetry | 分光光度法与比色法
Colorimetry measures the absorbance of light by a coloured solution at a specific wavelength. Select a wavelength complementary to the colour of the solution.
比色法测定有色溶液在特定波长下的吸光度。选择与溶液颜色互补的波长。
A calibration curve is prepared using a series of standard solutions with known concentrations. Zero the colorimeter with a blank (solvent without the analyte) before taking readings.
用一系列已知浓度的标准溶液制作校准曲线。测量前用空白溶液（不含分析物的溶剂）调零比色计。
Plot absorbance against concentration; the graph should be a straight line through the origin according to the Beer–Lambert law. Use the line to determine the concentration of an unknown sample.
以吸光度对浓度作图，根据比尔‑朗伯定律应为一条通过原点的直线。利用该直线确定未知样品的浓度。
For UV‑visible spectrophotometry, scan over a range of wavelengths to obtain the absorption spectrum. Identify the wavelength of maximum absorbance (λₘₐₓ) for maximum sensitivity.
对于紫外‑可见分光光度法，扫描一段波长范围得到吸收光谱。确定最大吸光度对应的波长 (λₘₐₓ) 以获得最佳灵敏度。
11. Data Handling and Uncertainty Analysis | 数据处理与不确定度分析
Record all raw measurements with the appropriate number of significant figures, reflecting the precision of the instrument. The last digit is always the uncertain one.
以适当的有效数字记录所有原始测量值，反映仪器的精度。最后一位数字总是可疑数字。
Determine the absolute uncertainty for each piece of apparatus. Common values: 50 cm³ burette ±0.05 cm³, 25 cm³ pipette ±0.06 cm³, 250 cm³ volumetric flask ±0.2 cm³, analytical balance ±0.001 g.
确定每件仪器的绝对不确定度。常见值：50 cm³ 滴定管 ±0.05 cm³，25 cm³ 移液管 ±0.06 cm³，250 cm³ 容量瓶 ±0.2 cm³，分析天平 ±0.001 g。
Percentage uncertainty = (Absolute uncertainty / Measured value) × 100%
Calculate the total percentage uncertainty for a measurement series. For multiplication or division, add the individual percentage uncertainties; for addition or subtraction, add the absolute uncertainties.
计算一个测量系列的总百分不确定度。乘法或除法计算时，叠加各项百分不确定度；加法或减法计算时，叠加绝对不确定度。
Distinguish between random errors (reduced by repeats) and systematic errors (reduced by calibration or changing procedure). Use error bars on graphs to represent uncertainty visually.
区分随机误差（通过重复测量减小）和系统误差（通过校准或改进程序减小）。在图表上使用误差棒直观表示不确定度。
12. Writing an Excellent IA or Required Practical Report | 撰写优秀的IA或必做实验报告
In the IB Individual Investigation (IA), clearly state a focused research question that links the independent and dependent variables. Provide background chemical theory and justify the choice of methodology.
在IB个人探究 (IA) 中，要明确提出一个能将自变量与因变量联系起来的重点研究问题。提供化学理论背景并证明方法选择的合理性。
Include a full list of equipment and chemicals with quantities and concentrations. Detail the procedure step-by-step so that another student could replicate it exactly.
列出完整的仪器与化学试剂清单，注明数量和浓度。逐步详述操作步骤，以便其他学生可以完全重复。
Record raw data in clearly labelled tables with units and uncertainties. Process the data using correct mathematical manipulations and show a sample calculation.
将原始数据记录在标注清晰的表格中，附有单位和不确定度。使用正确的数学方法处理数据并展示一个示例计算。
In the evaluation, discuss sources of error and suggest specific, practical improvements. Compare your result with literature values and calculate the percentage error.
在评估中讨论误差来源并提出具体可行的改进建议。将结果与文献值进行比较并计算百分误差。
For AQA required practicals, document the method, risk assessment, and results in your lab book. Tutors assess you against the Common Practical Assessment Criteria (CPAC): follows procedures, uses apparatus safely, makes accurate observations, and records, analyses, and evaluates data.
对于AQA必做实验，需在实验记录本中记录方法、风险评估和结果。教师根据通用实践评估标准 (CPAC) 对你进行评分：遵循操作程序、安全使用仪器、准确观察、记录、分析和评估数据。
Whether IB or AQA, the key to success is deliberate practice, meticulous recording, and a genuine curiosity about the chemical principles at work.
无论是IB还是AQA，成功的关键在于有意识的练习、一丝不苟的记录以及对化学原理真诚的好奇心。
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