📚 Making Entries: Recording Data in IGCSE Chemistry Practicals | IGCSE化学实验数据记录：规范填写要点
In IGCSE Chemistry practical work, 'making entries' is the skill of writing measurements, observations and calculated values into a results table clearly, completely and accurately. Examiners reward entries that carry full units in the headings, use precision that matches the apparatus, and describe what was actually seen rather than what the student thinks it means. This guide explains, step by step, how to make entries that meet Cambridge IGCSE standards for Paper 5 (Practical Test) and Paper 6 (Alternative to Practical).
在IGCSE化学实验中，"记录数据"（making entries）指的是把测量值、观察现象和计算结果清晰、完整、准确地填写进结果表格的能力。阅卷人会奖励那些在表头中写全单位、精度与仪器相匹配、并且如实描述"看到什么"而非"猜测是什么"的记录。本指南将分步骤讲解如何做出符合剑桥IGCSE Paper 5（实验操作考试）与 Paper 6（实验替代考试）标准的实验记录。
1. What Does 'Making Entries' Mean in IGCSE Chemistry? | IGCSE化学中"记录数据"指什么？
In practical chemistry, an entry is any item of information you write down while carrying out an experiment. Entries fall into three families: numerical readings such as mass, volume and temperature; descriptive observations such as colour changes, precipitates or bubbles of gas; and derived values that you calculate afterwards, such as an average titre or a number of moles.
在化学实验中，"记录条目"是你在做实验过程中写下的任何信息。记录可分为三类：质量、体积、温度等数值读数；颜色变化、沉淀、气泡等描述性观察；以及实验后计算得出的衍生值，例如平均滴定体积或物质的量。
In Cambridge IGCSE Chemistry, practical skills are assessed through Paper 5 (Practical Test) or Paper 6 (Alternative to Practical). Both papers award marks for entries that are accurate, complete and unambiguous, so the way you present data matters as much as the value itself.
在剑桥IGCSE化学中，实验技能通过 Paper 5（实验操作考试）或 Paper 6（实验替代考试）进行考查。两份试卷都会为准确、完整、无歧义的记录给分，因此数据的呈现方式与数据本身同样重要。
- Accurate entries are within the tolerance expected of the apparatus used. 准确的记录应落在所用仪器允许的误差范围内。
- Complete entries include every unit, every repeat and every required column. 完整的记录应包含全部单位、全部重复读数和全部必需栏目。
- Readable entries are neatly ruled, clearly labelled and free of untidy corrections. 可读的记录应表格清晰、标注明确、涂改规范。
2. The Structure of a Results Table | 结果表格的结构
A good results table has a clear title, column headings that include units, and the independent variable placed in the first column. If you change the volume of acid added, then volume belongs in the left-hand column and the measured temperature belongs in the right-hand column, because the reading depends on the volume you chose.
一个良好的结果表格应有清晰的标题、包含单位的列表头，并把自变量放在第一列。如果你改变加入酸的体积，那么体积应放在左列，测得的温度放在右列，因为温度读数取决于你所选择的体积。
Every column heading should show the quantity and its unit separated by a slash, for example Volume of acid added / cm³ or Temperature / °C. The cells themselves contain only numbers, never units, because repeating units in every cell wastes time and looks untidy.
每个列表头都应以斜线分隔物理量与单位，例如 Volume of acid added / cm³ 或 Temperature / °C。单元格内只填写数字，不写单位——在每个格子里重复单位既浪费时间，也不整洁。
| Volume of acid added / cm³ | Temperature / °C |
|---|---|
| 0 | 21.0 |
| 5 | 23.5 |
| 10 | 26.0 |
Rows and columns should be ruled with a pencil and ruler before you start collecting data, and the table should be drawn large enough to hold every repeat you expect to take. Space left at the bottom often means the last set of readings is squeezed in and the table becomes hard to read.
表格应在开始收集数据之前用铅笔和直尺画好，并且要留出足以容纳所有重复读数的空间。底部空间不足时，最后一组读数往往被挤在一起，使表格难以辨读。
3. Column Headings and Units: The Slash Rule | 列表头与单位：斜线规则
The slash rule is simple: write the quantity, then a forward slash, then the unit. 'Time / s', 'Mass of solid / g', 'Volume of gas / cm³' and 'Concentration / mol dm⁻³' all follow the rule. Never write 'Time in seconds' or 'Mass (g)' if you want the cleanest mark-scheme response.
斜线规则很简单：先写物理量，再写斜线，最后写单位。"Time / s""Mass of solid / g""Volume of gas / cm³""Concentration / mol dm⁻³" 都符合这一规则。若想让答案最贴近评分标准，就不要写 "Time in seconds" 或 "Mass (g)"。
Pay attention to units that are easy to confuse, especially in rate and titration work. A volume measured with a burette is in cm³, not dm³, and a concentration is usually in mol dm⁻³, not mol cm⁻³ or g dm⁻³ unless the question specifies a mass concentration.
要特别注意容易混淆的单位，尤其是在反应速率与滴定计算中。滴定管测得的体积单位是 cm³ 而不是 dm³；浓度通常写作 mol dm⁻³，除非题目明确要求质量浓度，否则不要写成 mol cm⁻³ 或 g dm⁻³。
- Volume of liquid in a burette or pipette: cm³. 滴定管或移液管中液体体积：cm³。
- Temperature change: °C (a difference in degrees Celsius). 温度变化：°C（摄氏温度差）。
- Time for a reaction to finish: s, or min if the change is slow. 反应完成时间：s；若变化缓慢可用 min。
- Mass of a solid weighed on a balance: g. 天平称量的固体质量：g。
- Amount of substance calculated from a formula: mol. 由公式计算出的物质的量：mol。
4. Precision, Decimal Places and Significant Figures | 精度、小数位与有效数字
Precision means the number of decimal places you record, and it should match the instrument you used. A two-decimal-place balance gives readings such as 2.46 g, a thermometer reading to the nearest 0.5 °C gives 24.5 °C, and a burette is read to two decimal places, so 24.50 cm³ is acceptable but 24.5 cm³ is not.
精度指的是你记录的小数位数，应与所用仪器相匹配。两位小数天平给出 2.46 g 这样的读数；可读到 0.5 °C 的温度计给出 24.5 °C；滴定管读数保留两位小数，因此 24.50 cm³ 可以接受，而 24.5 cm³ 不行。
Crucially, all readings in the same column must be recorded to the same number of decimal places, even when the value ends in zero. Writing 25, 24.5 and 24.30 in one column suggests three different instruments were used, which is never the case in an IGCSE practical.
关键在于，同一列中的所有读数必须保留相同的小数位，即使数值末尾是零也要补齐。在同一列中写 25、24.5 和 24.30，会让人以为使用了三种不同的仪器，而在IGCSE实验中这绝不可能。
When you average readings, the mean should carry the same number of decimal places as the readings themselves, or at most one more. For example, two concordant titres of 24.50 cm³ and 24.60 cm³ average as shown below.
计算平均值时，平均值应保留与原始读数相同的小数位，最多多一位。例如，两次吻合的滴定体积 24.50 cm³ 与 24.60 cm³ 的平均值如下所示。
Mean titre = (24.50 + 24.60) ÷ 2 = 24.55 cm³
5. Recording Observations Rather Than Interpretations | 记录观察事实，而非结论推断
An observation describes what your eyes can see; an interpretation explains what it means. 'A white precipitate formed' is an observation, while 'calcium carbonate was produced' is a conclusion that belongs in the inference column, if anywhere at all.
观察描述的是眼睛能看到的现象；推断解释的是现象的含义。"生成白色沉淀"是观察，而"生成了碳酸钙"属于结论，应放入推断栏（如果确有该栏的话）。
Good observational language is precise about colour, state and change. Write 'colourless solution turned pale blue', 'effervescence, gas relights a glowing splint' or 'the solid dissolved to give a colourless solution', rather than vague words such as 'it changed' or 'something happened'.
规范的观察用语要精确描述颜色、状态与变化。应写 "无色溶液变为浅蓝色""产生气泡，气体使带火星木条复燃" 或 "固体溶解，形成无色溶液"，而不是 "它变了" 或 "发生了反应" 这类含糊表述。
Remember that 'colourless' and 'white' are not interchangeable. A solution is colourless; a solid or a precipitate is white. Also avoid recording a colour as 'clear' when you mean colourless, since clear only means transparent.
请记住 "colourless（无色）" 与 "white（白色）" 不能互换：溶液是无色的，固体或沉淀是白色的。当你想说无色时，也不要写成 "clear"，因为 clear 只表示透明。
- Colour: name both the starting and finishing colour. 颜色：同时写出起始颜色与最终颜色。
- State: solid, solution, precipitate, gas, liquid layers. 状态：固体、溶液、沉淀、气体、分层液体。
- Change: dissolved, effervescence, heat evolved, colour faded. 变化：溶解、冒泡、放热、褪色。
- Smell and sound only when asked, and never taste anything in a school laboratory. 只有在要求时才记录气味和声音；在学校实验室中绝不品尝任何药品。
6. Making Entries in Qualitative Analysis Tables | 定性分析表格中的记录
Qualitative analysis questions usually give a three-column table: test, observation and inference. The entry in the test column must include the reagent and any condition, such as 'add dilute nitric acid, then silver nitrate solution', because a bare reagent name may not earn the mark.
定性分析题通常给出三列表格：实验、现象、推断。实验栏的记录必须包含试剂和条件，例如 "加入稀硝酸，再加入硝酸银溶液"，因为只写试剂名称可能拿不到分。
The observation column accepts only what was seen, and the inference column converts that into an ion or a gas. The pattern below shows how the three columns connect for common IGCSE tests.
现象栏只接受实际看到的内容，推断栏再把现象转换为离子或气体。下表展示了常见IGCSE检验中三栏之间的对应关系。
| Test | Observation | Inference |
|---|---|---|
| Add dilute nitric acid, then silver nitrate solution | White precipitate | Chloride ions, Cl⁻ |
| Add dilute sodium hydroxide solution | Pale blue precipitate | Copper(II) ions, Cu²⁺ |
| Add dilute hydrochloric acid | Effervescence, gas turns limewater milky | Carbonate ions, CO₃²⁻ |
7. Repeat Readings, Concordance and Averages | 重复读数、吻合性与平均值
Where a measurement is repeated, entries should include every reading, not just the ones you like. Titration tables normally contain a rough titration plus two or three accurate titrations, and the mean is calculated only from readings that agree closely, usually within 0.10 cm³ of each other.
凡有重复测量的地方，记录都应包含每一次读数，而不只是你满意的那几次。滴定表格通常包括一次粗略滴定和两到三次精确滴定，平均值只由彼此接近（通常相差在 0.10 cm³ 以内）的读数计算得出。
Anomalous results should be identified clearly, commonly with an asterisk and a note such as 'anomalous, not used in the mean'. Cross out mistakes in a table with a single straight line and write the corrected value beside it, so the examiner can still see what was recorded.
异常值应明确标出，常用星号并加注 "异常，不计入平均值"。表格中的错误用一条直线划掉，并在旁边写上更正后的数值，这样阅卷人仍能看到你原来的记录。
Never include a result you know is faulty simply to increase the number of readings, and never invent a repeat reading to make the mean look tidy. In Paper 5 the supervisor sees your raw data, and in Paper 6 the question often supplies readings for you to select from.
绝不要为了增加读数数量而把明知有问题的结果纳入平均，也绝不要编造重复读数让平均值看起来整齐。在 Paper 5 中监考教师会看到你的原始数据，在 Paper 6 中题目通常已经给出读数供你筛选。
8. Instrument-Specific Entries | 各类仪器的记录要求
Different apparatus has different precision, and matching that precision is one of the fastest ways to gain or lose marks. Learn the standard entries for the instruments you meet most often in IGCSE practicals, so you do not have to think about it under exam pressure.
不同仪器的精度不同，使记录精度与其匹配是最容易得分、也最容易失分的地方之一。请熟记IGCSE实验中最常见仪器的标准记录方式，这样在考场压力下就无需再思考。
| Apparatus | Typical entry | Note |
|---|---|---|
| Balance | 2.46 g, 2.50 g | Two decimal places, trailing zero included |
| Thermometer | 24.5 °C, 25.0 °C | Nearest 0.5 °C or 0.1 °C, depending on the scale |
| Burette | 0.00 cm³, 24.50 cm³ | Two decimal places, read the bottom of the meniscus |
| Measuring cylinder | 25 cm³, 10.5 cm³ | Nearest 1 cm³ or 0.5 cm³, less precise |
| Gas syringe | 45 cm³, 60 cm³ | Nearest 1 cm³, sometimes 0.5 cm³ |
Always read the scale, not the label. A 25 cm³ measuring cylinder cannot deliver 25.00 cm³, so recording that value shows a misunderstanding of the instrument rather than unusual skill.
始终读取刻度，而不是仪器标签。25 cm³ 量筒不可能量出 25.00 cm³，写出这样一个数值只会暴露你对仪器精度的误解，而不是显示技巧高超。
9. Making Entries in a Titration | 滴定实验的数据记录
A titration table needs columns for the final burette reading, the initial burette reading and the volume used, all in cm³ and all to two decimal places. Each accurate titration must have its own initial reading, even if the burette was not refilled, because the examiner is checking that you subtracted correctly.
滴定表格需要设置终读数、初读数和所用体积三列，单位均为 cm³，且都保留两位小数。每一次精确滴定都必须有自己的初读数，即使没有重新加液，因为阅卷人要看你的减法是否正确。
Volumes are found by simple subtraction, and the rough titration is never included in the mean. A typical set of entries looks like the table below.
所用体积通过简单相减得出，粗略滴定不计入平均值。一组典型的记录如下表所示。
| Titration | Final reading / cm³ | Initial reading / cm³ | Volume used / cm³ |
|---|---|---|---|
| Rough | 24.80 | 0.00 | 24.80 |
| 1 | 24.60 | 0.00 | 24.60 |
| 2 | 48.90 | 24.60 | 24.30 |
Volume used = final reading − initial reading
In the example above the second titration is anomalous, so the mean is calculated from the rough and first titrations only if the question asks for a value, or preferably from two further concordant runs.
上例中第二次滴定为异常值，因此若题目要求计算结果，平均值只由粗略滴定和第一次滴定（或更理想地，再补做两次吻合滴定）求得。
10. Entries for Continuous Change: Rates and Temperature | 连续变化的记录：速率与温度
When a quantity changes during the experiment, entries must be taken at regular intervals and written in a table with the independent variable first. For a rate experiment measuring gas volume, time goes in the first column and the total volume of gas collected goes in the second.
当某个量在实验过程中持续变化时，记录必须按等间隔时间采集，并填入自变量在前的表格。例如测定气体体积的速率实验，时间放在第一列，累计收集到的气体体积放在第二列。
Volume recorded at each time must be the total collected since the start, not the volume gained since the last reading, unless the question states otherwise. For temperature work, record the temperature before adding the reagent, the maximum or minimum reached, and the change calculated from them.
每一时刻记录的气体体积应是自开始以来累计收集的总量，而不是距上次读数新增的量，除非题目另有说明。做温度实验时，应记录加入试剂前的温度、达到的最高或最低温度，以及由两者算出的变化量。
- Start the timer at the moment the reagents are mixed. 计时从试剂混合的那一刻开始。
- Keep the interval constant, for example every 20 s. 保持时间间隔恒定，例如每 20 s 记录一次。
- Continue until the reading no longer changes, or the stated time is reached. 持续记录到读数不再变化或达到规定时间为止。
- Plot the entries on a graph with labelled axes and units. 将记录数据作图，坐标轴须有标注与单位。
11. Calculated and Derived Entries | 计算值与衍生数据的记录
Calculated entries sit in their own columns or below the table, and they must be traceable back to the raw readings. Show the working, keep units throughout and give the answer to a sensible number of significant figures, usually three for IGCSE calculations.
计算值应放在单独一列或表格下方，并且必须能追溯到原始读数。要写出计算过程、全程带单位，并把答案保留到合理的有效数字位数，IGCSE计算通常保留三位。
For titration calculations, the route from a mean titre to a concentration follows a fixed sequence: convert cm³ to dm³, calculate moles of the known solution, apply the mole ratio from the equation, then divide by the volume of the unknown solution.
在滴定计算中，从平均滴定体积到浓度的路径是固定顺序：先把 cm³ 换算为 dm³，计算已知溶液的物质的量，再按化学方程式的计量比换算，最后除以未知溶液的体积。
n = c × V ÷ 1000
c = n ÷ V × 1000
Round only at the end of a calculation. Rounding each intermediate value to two or three significant figures introduces errors that can push a final answer outside the accepted range, especially in multi-step mole calculations.
只在计算的最后一步取整。若在每一步中间值就取两三位有效数字，误差会逐渐累积，使最终答案超出可接受范围，在多步物质的量计算中尤其明显。
12. Examiner Expectations and Common Errors | 阅卷人期待与常见错误
Mark schemes for practical papers reward consistency and honesty far more than perfect numbers. An examiner looks for complete headings, identical decimal places down each column, observations that describe rather than interpret, and repeats that are recorded and averaged properly.
实验卷的评分标准更看重一致性与真实性，而不是完美的数值。阅卷人关注的是：表头是否完整、每列小数位是否一致、观察是否描述而非推断、重复读数是否记录并正确取平均。
The most common lost marks are easy to avoid once you know them: units written inside cells, readings given to inconsistent decimal places, a mean that includes an anomalous value, and observations that state a conclusion such as 'carbon dioxide was produced' rather than 'gas turned limewater milky'.
最常见的失分点一旦了解就很容易避免：单位写进单元格、读数小数位不一致、平均值中混入了异常值，以及把结论当现象写，例如写 "生成了二氧化碳" 而不是 "气体使石灰水变浑浊"。
- Write every entry in pen, and correct mistakes with a single line plus your initials. 所有记录用钢笔书写，改错时划一条线并签上姓名缩写。
- Check that each column has the same number of entries as the column beside it. 检查每一列的行数与相邻列是否一致。
- Check that no cell is empty where a reading should exist. 检查应填写读数的地方是否留空。
- Check units in every heading before you turn the page. 翻页前再核对一遍每个表头的单位。
- Check that the mean excludes anomalous values and matches the decimal places of the readings. 检查平均值是否排除了异常值，并与读数小数位一致。
If you practise writing entries in this format during every practical lesson, the routine becomes automatic, and in the examination you can spend your thinking time on the chemistry rather than on the table.
如果你在每一次实验课上都按这一格式练习记录，这套流程就会变成本能；到了考场上，你的思考时间就能真正用在化学本身，而不是浪费在表格上。
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