📚 Key Practical Assessment Points for Year 7 Cambridge Chemistry | Year 7 剑桥化学实验/实践考核要点
Practical work is a core part of the Year 7 Cambridge Chemistry syllabus. Your teacher will assess how safely you handle equipment, how carefully you make observations, and how well you can analyse simple experimental data. This guide breaks down the key skills you need to show during practical assessments, from lighting a Bunsen burner to drawing conclusions from your results.
实验操作是 Year 7 剑桥化学课程的核心部分。老师会评估你使用仪器的安全性、观察的细致程度，以及分析简单实验数据的能力。本指南详细分解了你在实践考核中需要展示的关键技能，从点燃本生灯到根据结果得出结论，一应俱全。
1. Safety in the Lab | 实验室安全
Always tie back long hair and tuck in loose clothing, scarves or ties before entering the lab. Long hair can dip into flames or chemicals, and dangling sleeves may knock over apparatus.
进入实验室前，一定要把长发扎起来，并将宽松的衣物、围巾或领带塞好。长发可能垂入火焰或化学品中，悬垂的袖子可能会碰倒仪器。
Wear chemical-splash safety goggles whenever heating, mixing solutions or handling acids and alkalis. Ordinary spectacles are not a substitute for goggles.
在加热、混合溶液或处理酸和碱时，必须佩戴防化学飞溅的护目镜。普通眼镜不能替代护目镜。
Never taste any chemical or put your nose directly over an open container to smell it. Instead, use the ‘wafting’ technique: gently wave your hand over the mouth of the container to direct a tiny amount of vapour towards your nose.
切勿品尝任何化学品，也不要把鼻子直接凑到开口容器上方去闻。应使用“扇闻”法：用手在容器口上方轻轻扇动，使微量蒸汽飘向鼻子。
Know the location of the fire extinguisher, fire blanket and eyewash station before starting any practical. Report all spills, breakages or accidents to your teacher immediately, no matter how small.
开始任何实验前，要了解灭火器、灭火毯和洗眼器的位置。任何溢出、破损或意外，无论多小，都要立即报告老师。
When using a Bunsen burner, always place it in the centre of the bench, away from the edge and from papers or books. Check that the rubber tubing is not cracked before lighting.
使用本生灯时，要把它放在工作台中央，远离边缘、纸张或书本。点燃前检查橡胶管是否有裂纹。
2. Recognising and Using Common Lab Equipment | 识别与使用常见实验仪器
You will be expected to name and safely use a range of apparatus: beakers, conical flasks, test tubes, boiling tubes, measuring cylinders, Bunsen burners, tripods, gauzes, heatproof mats, evaporating basins, filter funnels and stirring rods.
你需要能够说出并安全使用一系列仪器：烧杯、锥形瓶、试管、沸腾管、量筒、本生灯、三脚架、石棉网、隔热垫、蒸发皿、过滤漏斗和搅拌棒。
A measuring cylinder is read at the bottom of the liquid curve, called the meniscus. Your eye must be level with the meniscus to avoid a parallax error. Never pick up a hot beaker with wet hands or without using tongs.
量筒的读数应读液体弯月面的最底部。眼睛必须与弯月面水平，以避免视差错误。切勿用湿手或不使用坩埚钳就去拿取热烧杯。
Test tubes should be held with a test tube holder when being heated, and they must be pointed away from yourself and others. Heating a closed test tube can cause an explosion, so never put a bung on a tube you are heating.
加热试管时要用试管夹持住，试管口必须朝向无人的方向。加热封闭的试管可能引起爆炸，因此切勿给正在加热的试管塞上塞子。
An evaporating basin is used to concentrate a solution by heating gently above a water bath or on a pipe-clay triangle. It should never be heated so strongly that the contents spit.
蒸发皿用于通过水浴加热或放在泥三角上缓慢加热来浓缩溶液。加热不应过猛，以免内容物飞溅。
3. Measuring and Recording Data | 测量与记录数据
Always record measurements using appropriate units: mass in grams (g), volume in centimetres cubed (cm³) or millilitres (ml), and temperature in degrees Celsius (°C). Choose the measuring instrument that gives the best precision for your task – for instance, use a 10 cm³ measuring cylinder when you need to measure small volumes of acid, rather than a 100 cm³ cylinder.
记录测量值时要使用恰当的单位：质量用克（g），体积用立方厘米（cm³）或毫升（ml），温度用摄氏度（°C）。选择能为你的任务提供最佳精度的测量仪器——例如，需要量取少量酸液时，用 10 cm³ 量筒，而不用 100 cm³ 量筒。
All readings should be written immediately into a results table, not on scraps of paper. The table must have clear headings with units in brackets, e.g. ‘Temperature at start (°C)’. Draw the table in pencil and use a ruler.
所有读数应立即记录到结果表中，而不是记在碎纸片上。表格必须有清晰的标题，单位用括号括起来，例如“起始温度（°C）”。用铅笔和直尺绘制表格。
Repeat measurements are important for reliability. Where possible, take at least two or three readings and then calculate the mean. Anomalous results – those that do not fit the pattern – should be identified and discussed, but never erased.
重复测量对于可靠性很重要。在可能的情况下，至少读取两到三次数值，然后计算平均值。异常结果——即不符合规律的数据——应予以识别和讨论，但绝不能擦除。
4. Heating Substances Safely | 安全加热物质
The Bunsen burner has a safety flame (yellow) and a roaring blue flame. The blue flame is hotter and is used for heating; the yellow flame is visible and safer when not heating. Learn to change between them by adjusting the air hole.
本生灯有安全焰（黄色）和强热蓝焰。蓝焰温度更高，用于加热；黄焰可见，在不加热时更安全。要学会通过调节气孔在两种火焰间切换。
When heating a liquid in a test tube, move the tube gently in and out of the flame to avoid bumping. Always use a small amount of solid or liquid to begin with and add boiling chips if directed by your teacher.
在试管中加热液体时，要轻轻将试管移进移出火焰，以避免暴沸。开始实验时总是先用少量固体或液体，并在老师指示下加入沸石。
To heat a beaker of water, place it on a tripod with a wire gauze. Light the burner, place it under the gauze, and adjust to a blue flame. Never leave a lit burner unattended, and turn off the gas as soon as heating is finished.
加热烧杯中的水时，将其放在三脚架和石棉网上。点燃本生灯，置于石棉网下，调整到蓝焰。点燃的本生灯绝不可无人看管；加热完毕立即关闭燃气。
When heating a solid in an evaporating dish on a clay triangle, start with a gentle heat and increase gradually. Stir the solid with a glass rod to spread the heat evenly and prevent localised decomposition.
在泥三角上加热蒸发皿中的固体时，先从微热开始，逐渐加大火力。用玻璃棒搅拌固体，使热量均匀分散，防止局部过热分解。
5. Making Clear, Detailed Observations | 进行清晰、详细的观察
Observations should describe colour changes, fizzing (effervescence), temperature changes, the appearance of a precipitate, or a change in state. Instead of saying ‘the liquid changed’, write ‘the colourless solution turned cloudy white and a thick white solid settled at the bottom’.
观察应描述颜色变化、冒泡（起泡）、温度变化、沉淀的出现或状态变化。不要只说“液体变了”，要写“无色溶液变成混浊的白色，并在底部沉降出一层厚实的白色固体”。
Use all your senses that are safe – sight and touch in particular. Check if a test tube becomes warm or cool to the touch (exothermic or endothermic), but only with the back of your hand and after checking with your teacher.
运用所有安全的感官——尤其是视觉和触觉。用手背感受试管变得温热还是冰凉（放热或吸热），但必须先征求老师同意。
Always note the starting appearance of reactants. For example, ‘copper sulfate crystals are blue, diamond-shaped, and dry’ gives a full description that helps identify any change later.
始终记录反应物的初始外观。例如，“硫酸铜晶体为蓝色、菱形、干燥”，这样的完整描述有助于后续识别任何变化。
If a gas is produced, you may be asked to test it. You will need to know the standard tests: glowing splint for oxygen (relights), lit splint for hydrogen (squeaky pop), and limewater for carbon dioxide (turns milky).
如果产生气体，你可能会被要求进行检验。你需要知道标准检验方法：用带火星的木条检验氧气（复燃），用点燃的木条检验氢气（发出爆鸣声），用石灰水检验二氧化碳（变浑浊）。
6. Identifying Variables and Fair Testing | 识别变量与公平测试
A fair test is one where only the independent variable is changed, everything else (control variables) is kept the same, and the dependent variable is measured accurately. You must be able to identify each kind of variable in a given experiment.
公平测试是指只改变自变量，其他一切（控制变量）保持不变，并准确测量因变量的实验。你必须能在给定实验中识别出每一类变量。
For example, if you are investigating how the volume of acid affects the temperature rise when mixed with an alkali, the volume of acid is the independent variable, the volume and concentration of alkali are control variables, and the temperature rise is the dependent variable.
例如，在研究酸的体积如何影响与碱混合时的温升时，酸的体积是自变量，碱的体积和浓度是控制变量，温升是因变量。
Control variables must be measured and recorded, not just listed. Say ‘we used exactly 25.0 cm³ of sodium hydroxide solution each time’ instead of ‘we kept the alkali the same’.
控制变量必须被测量和记录，而不仅仅是列出。要说“每次使用恰好 25.0 cm³ 氢氧化钠溶液”，而不是“碱保持不变”。
In investigations involving heating, the size of the burner flame, the height of the tripod, and the starting temperature of water must be controlled. Always write a simple statement like ‘The results are valid because we kept the flame size constant and used the same beaker.’
在涉及加热的研究中，本生灯火焰的大小、三脚架的高度以及水的起始温度都必须控制。永远要写出一个简单的陈述，比如“结果有效，因为我们保持了火焰大小恒定，并使用同一个烧杯”。
7. Carrying Out a Method Accurately | 准确执行实验方法
Read the method all the way through before touching any equipment. Circle or underline key quantities and safety instructions. If you are asked to write the method yourself, number each step and use a clear, command word at the start of each sentence, such as ‘Measure’, ‘Add’, ‘Stir’, ‘Heat’.
在接触任何仪器之前，先通读整个方法。圈出或划出关键用量和安全说明。如果要求你自己编写方法，要为每个步骤编号，并在每句开头使用清晰的动词，如“量取”、“加入”、“搅拌”、“加热”。
When measuring out liquids, use a clean measuring cylinder and pipette. Touch the tip of the pipette to the inside wall of the flask to allow the last drop to drain. Do not blow out the last drop of a non-blowout pipette.
量取液体时，使用清洁的量筒和移液管。将移液管的尖端接触瓶壁，让最后一滴流出。非吹出式移液管的最后一滴不要吹出。
If you need to dissolve a solid, add it to the solvent little by little and stir with a glass rod. Heating the solvent gently will speed up dissolving, but you must record whether heating was used.
如果需要溶解固体，要少量多次地将其加入溶剂中，并用玻璃棒搅拌。微微加热溶剂可加速溶解，但你必须记录是否使用了加热。
During filtration, fold the filter paper into a cone that fits snugly inside the funnel. Wet the paper slightly with distilled water so it sticks. Pour the mixture down a glass rod into the funnel to avoid splashing.
过滤时，将滤纸折叠成能与漏斗内壁紧密贴合的圆锥形。用蒸馏水稍稍润湿滤纸，让它贴住。将混合物沿玻璃棒倒入漏斗，以防溅出。
8. Presenting Results: Tables and Graphs | 呈现结果：表格与图表
Data should first be placed in an organised table with ruled lines and clear headings. The independent variable is usually in the left-hand column, and the dependent variable in the right-hand column(s).
数据应首先放入一个线条清晰、标题明确的规整表格中。自变量通常放在左侧栏，因变量放在右侧栏。
When plotting a line graph, label the x‑axis (independent variable) and y‑axis (dependent variable) with both the quantity and its unit, e.g. ‘Volume of acid (cm³)’. Choose a sensible scale that uses most of the graph paper, and mark data points with small crosses.
绘制线状图时，用数量和单位标记 x 轴（自变量）和 y 轴（因变量），如“酸的体积（cm³）”。选择能充分利用大部分图纸的合理刻度，并用小叉号标记数据点。
If the investigation produces discrete categories (e.g. types of metal), draw a bar chart. Bars must be equal width, separated by gaps, and clearly labelled. For continuous data showing a trend, draw a best-fit line or smooth curve; never simply connect the dots dot-to-dot.
如果调查产生的是离散类别（例如金属种类），则绘制条形图。条形宽度必须相等，之间有间隙，并清晰标注。对于显示趋势的连续数据，要画一条最佳拟合线或光滑曲线；绝不能只是点对点连线。
Graphs provide a visual pattern. You will be assessed on your ability to describe what the line shows: ‘As the volume of acid increased, the maximum temperature rise increased steadily until 20 cm³, after which it levelled off.’
图表提供可视化的模式。你需要展现描述线条含义的能力：“随着酸的体积增加，最大温升稳步增大，直到 20 cm³ 后趋于平稳。”
9. Drawing Conclusions from Evidence | 根据证据得出结论
A conclusion must refer back to the data and link it to the original question or hypothesis. Start with ‘The results show that…’ and then state the relationship between the independent and dependent variables, using numbers from your table or graph to support it.
结论必须回到数据上，并将其与最初的问题或假设联系起来。以“结果表明……”开头，然后陈述自变量和因变量之间的关系，用表格或图表中的数字加以支撑。
If you were testing the statement ‘copper sulfate dissolves faster in hot water’, a valid conclusion would be: ‘At 20 °C, 2.0 g of copper sulfate dissolved in 45 seconds; at 60 °C it took only 12 seconds. This shows that temperature increases the rate of dissolving.’
如果你在检验“硫酸铜在热水中溶解得更快”这一陈述，一个有效的结论将是：“在 20 °C 时，2.0 g 硫酸铜用了 45 秒溶解；在 60 °C 时仅用了 12 秒。这表明温度加快了溶解速率。”
You should also state whether the data supports the prediction. Instead of saying ‘my hypothesis was correct’, write ‘the data supports the hypothesis because as temperature rose, the time to dissolve consistently decreased.’
你还应说明数据是否支持预测。不要说“我的假设正确”，而要写“数据支持假设，因为随着温度升高，溶解时间持续减少。”
If there is not enough data to be certain, say: ‘More repeats at additional temperatures would be needed to confirm this pattern.’
如果没有足够的数据来确认，应说：“需要在更多温度下进行额外的重复实验，才能确认这一模式。”
10. Evaluating the Experiment and Suggesting Improvements | 评估实验并提出改进
Evaluation is about judging how good your method and results are. Identify at least one source of error or limitation – for example, ‘the thermometer may not have been read at exactly one minute because the stopwatch and the thermometer had to be watched at the same time.’
评估是判断你的方法和结果的质量。至少指出一个误差来源或局限——例如，“由于要同时看秒表和温度计，可能无法正好在一分钟时读取温度计。”
Distinguish between random errors (which cause readings to scatter either side of the true value) and systematic errors (which cause all readings to be consistently too high or too low). For instance, forgetting to reset the balance to zero would be a systematic error.
区分随机误差（导致读数在真值两侧分散）和系统误差（导致所有读数始终偏高或偏低）。例如，忘记将天平调零就是一种系统误差。
Suggest specific, practical improvements. Instead of ‘do it more carefully’, say ‘use a data logger with a temperature probe to record the temperature every second automatically, removing human reaction time error.’
提出具体、切实的改进建议。不要说“更仔细地操作”，而要说“使用带有温度探头的数据记录器，每秒自动记录温度，消除人为反应时间误差”。
Also comment on whether you have enough data. If only two values of the independent variable were explored, recommend using a wider range with smaller intervals, such as testing acid volumes from 5 cm³ to 40 cm³ in steps of 5 cm³.
同时评价数据是否足够。如果只探索了两个自变量值，建议使用范围更广、间隔更小的数值，例如测试 5 cm³ 到 40 cm³ 的酸量，每次增量 5 cm³。
Finally, state how reliable you think the results are. Use phrases like ‘The repeats were close together, with a range of only 0.2 °C, so the results are quite reliable.’
最后，说明你认为结果的可靠性如何。可使用这样的措辞：“重复测量值非常接近，范围仅 0.2 °C，因此结果相当可靠。”
Published by TutorHao | Chemistry Revision Series | aleveler.com
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