📚 Year 7 CIE Chemistry: Key Points for Experimental/Practical Assessment | Year 7 CIE 化学：实验/实践考核要点
Practical assessments in Year 7 CIE Chemistry focus on developing core laboratory skills, understanding safety procedures, and accurately observing and recording results. This article covers the key points you need to master for your experimental exams, from using a Bunsen burner to testing gases and drawing conclusions.
Year 7 CIE 化学的实验考核着重培养核心实验技能、理解安全规程，并准确观察与记录结果。本文涵盖你需要掌握的实验考核要点，从本生灯的使用到气体检验和得出结论。
1. Laboratory Safety Rules | 实验室安全规则
Always wear safety goggles to protect your eyes from splashes and harmful substances. Tie back long hair and avoid loose clothing that could catch fire. Never eat or drink in the laboratory, and wash your hands after handling chemicals.
务必佩戴护目镜，保护眼睛免受飞溅和有害物质的伤害。将长发束起，避免穿着可能着火的宽松衣物。严禁在实验室内饮食，接触化学品后要洗手。
Know the location of the fire extinguisher, eyewash station, and first aid kit. If you spill a chemical on your skin, rinse it immediately with plenty of water and inform your teacher. Always work in a well-ventilated area and handle hot apparatus with tongs.
了解灭火器、洗眼站和急救箱的位置。若化学品溅到皮肤上，立即用大量水冲洗并告知老师。始终在通风良好的区域工作，用坩埚钳夹取热仪器。
Follow your teacher's instructions carefully and never mix chemicals unless told to do so. Dispose of waste as directed, and always label any test tubes or beakers containing substances.
仔细听从老师的指导，未经指示切勿随意混合化学品。按规定处理废弃物，并始终为盛有物质的试管或烧杯贴上标签。
2. Using a Bunsen Burner | 本生灯的使用
A Bunsen burner produces a flame by mixing gas with air. You must learn to light it safely: first close the air hole, light a splint, then turn on the gas and bring the splint to the top of the barrel. Never lean over the burner.
本生灯通过混合燃气与空气产生火焰。你必须学会安全点燃：先关闭气孔，点燃引火条，然后打开燃气，将引火条靠近灯管顶部。切勿俯身于本生灯上方。
The 'safety flame' (yellow) is visible but cooler, used when the burner is not heating anything. The 'roaring flame' (blue) is hotter and quieter, with the air hole fully open. The hottest part of the flame is just above the inner blue cone.
“安全焰”（黄色）可见但温度较低，用于本生灯不加热时。“轰鸣焰”（蓝色）更热更安静，气孔全开。火焰最热的部分在内层蓝色锥体的上方。
Always turn off the gas immediately after use and allow the burner to cool before putting it away. Never touch the barrel while it is hot.
使用后务必立即关闭燃气，待本生灯冷却后再收好。灯管灼热时切勿触碰。
3. Measuring Volumes of Liquids | 液体体积的测量
Use a measuring cylinder to measure liquid volumes accurately. Place it on a flat surface and read the bottom of the curved surface (the meniscus) at eye level. For example, if the meniscus sits between 23 cm³ and 24 cm³, the reading is 23.5 cm³.
使用量筒精确测量液体体积。将其放置在平坦表面上，视线与凹液面底部平齐读取数值。例如，若凹液面位于 23 cm³ 与 24 cm³ 之间，读数为 23.5 cm³。
Always choose a cylinder of appropriate size for the volume you need. A 10 cm³ cylinder gives more accurate readings for small volumes than a 100 cm³ cylinder. Never use a pipette or burette without guidance from your teacher.
始终根据需要量取的体积选择合适大小的量筒。对于小体积，10 cm³ 量筒比 100 cm³ 量筒读数更精确。未经老师指导，切勿使用移液管或滴定管。
When transferring liquids, use a dropping pipette to add the last few drops carefully. This prevents you from exceeding the required volume.
转移液体时，使用胶头滴管小心地滴加最后几滴，以免超出所需体积。
4. Handling Solids and Using a Balance | 固体处理与天平使用
Use a spatula to transfer solid chemicals from a container. Do not use your hands, as many chemicals can irritate the skin. Weigh solids on a balance: place a weighing boat or piece of paper on the pan, then press the tare button to zero the reading before adding the solid.
用药匙从容器中转移固体化学品。勿用手接触，许多化学品会刺激皮肤。用天平称量固体：将称量舟或纸放在秤盘上，然后按去皮键归零，再加入固体。
Record the mass to at least one decimal place (e.g., 5.2 g). If you weigh out too much, do not return the excess to the original container; dispose of it as instructed.
记录质量至少精确到一位小数（如 5.2 g）。若称取过多，不要将多余部分放回原瓶；按指示处理掉。
When timing dissolving, use a stopwatch and add the solid to the liquid only when you are ready to start timing.
进行溶解计时时，使用秒表，准备开始计时时才将固体加入液体中。
5. Heating and Cooling Substances | 加热与冷却物质
When heating a liquid in a test tube, point the mouth away from yourself and others. Use a test tube holder and move the tube gently back and forth through the flame. Never fill the tube more than one-third full to avoid vigorous boiling and splashing.
在试管中加热液体时，管口朝向远离自己和他人的方向。使用试管夹夹住试管，在火焰中来回缓慢移动。试管内液体不超过三分之一，以防剧烈沸腾飞溅。
To heat solids, use a crucible or an evaporating dish on a pipe-clay triangle. Always allow hot equipment to cool on a heatproof mat. Never place hot glass directly on a cold surface, as it may crack.
加热固体时，使用坩埚或蒸发皿，置于泥三角上。始终让灼热的仪器在耐热垫上冷却。切勿将热玻璃器皿直接放在冷表面上，否则可能破裂。
When measuring temperature changes, stir the liquid gently with the thermometer and wait for a steady reading. Avoid touching the sides of the container.
测量温度变化时，用温度计轻轻搅拌液体，待读数稳定后读取。避免温度计接触容器壁。
6. Observing Changes: Physical and Chemical | 观察变化：物理变化与化学变化
Physical changes do not produce new substances. Examples include melting ice, boiling water, and dissolving salt. During these changes, the mass usually remains the same, and the process is often reversible.
物理变化不产生新物质。例子包括冰融化、水沸腾和盐溶解。在这些变化中，质量通常保持不变，过程常可逆。
Chemical changes produce one or more new substances. Signs include colour changes, gas production (bubbles or fizzing), temperature changes, and the formation of a precipitate (solid from two liquids). A chemical change is often irreversible.
化学变化产生一种或多种新物质。迹象包括颜色变化、气体产生（气泡或嘶嘶声）、温度变化和沉淀生成（两种液体混合产生固体）。化学变化常不可逆。
In your practical assessment, you may be asked to decide whether a change is physical or chemical based on these observations. Always record any temperature change, gas produced, or colour shift.
在实验考核中，你可能会被要求根据这些观察结果判断变化是物理还是化学变化。务必记录任何温度变化、生成的气体或颜色转变。
7. Recording Observations and Data | 记录观察与数据
Write down what you see, smell (only if instructed to waft), and measure during the experiment. Use clear, concise language and note the time if events occur at intervals. For example: 'At 30 s, the solution turned cloudy.'
写下你在实验中看到的、闻到的（仅在老师指示下扇闻）和测量的结果。使用清晰简洁的语言，若事件间隔发生，记录时间。例如：“30 秒时，溶液变浑浊”。
Record numerical data in a table as you collect it. Do not wait until the end of the experiment, as you might forget values. Always include correct units, such as cm³, g, °C, or s.
在采集数据时将其记录在表格中。不要等到实验结束才记录，以免遗忘数值。始终包含正确单位，如 cm³、g、°C 或 s。
If an observation is 'no change', write that down too. Such negative results are important for drawing conclusions.
若观察结果为“无变化”，也请记录下来。这类阴性结果对得出结论很重要。
8. Drawing Tables and Graphs | 绘制表格与图表
Design a results table before you start the experiment. The first column should show the variable you change (independent variable), and the second column the variable you measure (dependent variable). Headings must include units, e.g., 'Temperature / °C'.
实验开始前设计结果表格。第一列应显示你改变的变量（自变量），第二列显示你测量的变量（因变量）。表头必须包含单位，如“温度 / °C”。
When drawing a graph, use a pencil and ruler. Plot the independent variable on the horizontal axis (x-axis) and the dependent variable on the vertical axis (y-axis). Label each axis clearly with the quantity and unit. Add an appropriate title.
绘图时使用铅笔和直尺。将自变量标在横轴（x 轴）上，因变量标在纵轴（y 轴）上。清楚标注每条轴的物理量和单位。添加合适的标题。
Choose scales that make good use of the graph paper and allow you to plot points accurately. Do not use a broken scale unless your data values start far from zero, and always mark the break clearly.
选择能充分利用坐标纸的刻度，以便精确描点。除非数据值远离零起点，否则不要使用截断刻度，若使用必须清楚标示断点。
Finally, draw a line or curve of best fit through the points. In Year 7, this is usually a straight line. Remember that the line should follow the trend, not necessarily pass through every point.
最后，通过各点画一条最佳拟合线或曲线。在 Year 7 中，通常是直线。记住，线要沿着趋势，不一定经过每个点。
9. Drawing Conclusions from Experiments | 从实验中得出结论
Your conclusion should refer directly to your results. State the relationship you have found between the independent and dependent variables. For example: 'As the temperature increased, the time for the tablet to dissolve decreased.'
你的结论应直接引用结果。陈述你发现的自变量与因变量之间的关系。例如：“随着温度升高，药片溶解的时间缩短”。
Use the data to back up your statements. You might say: 'At 20 °C, the dissolving time was 80 s, but at 40 °C it was only 40 s.' Compare your results with any scientific knowledge you have learned in class.
用数据支持你的陈述。你可以说：“20 °C 时，溶解时间为 80 秒，但 40 °C 时仅为 40 秒”。将你的结果与课堂上学到的科学知识进行比较。
If your results do not match the expected outcome, suggest why this might have happened. Do not alter your results to fit a pattern; honesty is vital.
如果你的结果与预期不一致，提出可能的原因。不要为适应模式而篡改结果；诚实至关重要。
10. Identifying Sources of Error and Improvements | 识别误差来源与改进
No experiment is perfect. Common errors include reading the meniscus incorrectly, not starting the stopwatch at the exact moment, heat loss to the surroundings, and difficulty in judging colour changes by eye.
没有完美的实验。常见误差包括凹液面读数不准、秒表未在精确时刻启动、热量散失到周围环境以及肉眼判断颜色变化的困难。
Suggest specific improvements. For example, use a temperature sensor and data logger instead of a thermometer to measure small temperature changes more accurately. Repeat the experiment and calculate a mean to reduce random errors.
提出具体的改进建议。例如，使用温度传感器和数据记录器代替温度计，以更精确地测量微小的温度变化。重复实验并计算平均值以减少随机误差。
In your practical assessment, you will often be asked to evaluate your method. Think about what equipment could be changed and how you could control variables more tightly.
在实验考核中，经常会被要求评价你的方法。思考哪些仪器可以更换，以及如何更严格地控制变量。
11. Common Practical Techniques: Filtration and Evaporation | 常见实验技术：过滤与蒸发
Filtration separates an insoluble solid from a liquid. Fold a filter paper into a cone and place it in a funnel. Pour the mixture slowly into the funnel. The liquid (filtrate) passes through, and the solid (residue) stays on the paper.
过滤将不溶性固体从液体中分离。将滤纸折叠成锥形放入漏斗。将混合物缓慢倒入漏斗。液体（滤液）通过，固体（残渣）留在滤纸上。
Evaporation is used to obtain a dissolved solid (solute) from a solution. Pour the solution into an evaporating dish and heat it gently using a water bath or Bunsen burner. Stop heating when crystals start to appear, and leave the dish to cool slowly to form larger crystals.
蒸发用于从溶液中获取溶解的固体（溶质）。将溶液倒入蒸发皿，用水浴或本生灯缓慢加热。当晶体开始出现时停止加热，让蒸发皿缓慢冷却以形成较大的晶体。
Remember never to evaporate the solution to complete dryness over a strong flame, as the solid may spit. Always wear safety goggles during both techniques.
记住，切勿在强火上将溶液蒸干，因为固体会飞溅。进行这两项操作时务必佩戴护目镜。
12. Testing Gases: Oxygen, Carbon Dioxide, Hydrogen | 气体检验：氧气、二氧化碳、氢气
To test for oxygen, hold a glowing splint near the mouth of a test tube containing the gas. If the splint relights, oxygen is present. This is because oxygen supports combustion.
检验氧气时，将带火星的木条靠近装有所述气体的试管口。若木条复燃，则有氧气存在。这是因为氧气支持燃烧。
To test for carbon dioxide, bubble the gas through limewater (calcium hydroxide solution). If the limewater turns milky or cloudy, carbon dioxide is present. This is due to the formation of insoluble calcium carbonate.
检验二氧化碳时，将气体通入石灰水（氢氧化钙溶液）。若石灰水变浑浊或呈乳白色，则有二氧化碳存在。这是由于生成了不溶性碳酸钙。
To test for hydrogen, hold a lit splint near the mouth of the test tube. A 'squeaky pop' sound indicates that hydrogen is present. Hydrogen is highly flammable, so only use a small amount.
检验氢气时，将点燃的木条靠近试管口。听到“噗”的爆鸣声表明有氢气存在。氢气极易燃，因此只使用少量。
You must be able to identify the gas produced in common reactions, such as magnesium with acid giving hydrogen, or thermal decomposition of a carbonate giving carbon dioxide.
你必须能够识别常见反应中生成的气体，例如镁与酸反应产生氢气，或碳酸盐热分解产生二氧化碳。
Published by TutorHao | Chemistry Revision Series | aleveler.com
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