📚 Year 7 CCEA Chemistry: Experiment and Practical Assessment Key Points | Year 7 CCEA 化学：实验/实践考核要点
In Year 7 CCEA Chemistry, practical skills are just as important as theoretical knowledge. This article covers the key points you need to master for your practical assessments, including safety rules, using equipment, making measurements, and recording observations. Mastering these skills will help you achieve high marks in experiments and prepare you for future science studies.
在Year 7 CCEA化学中，实践技能与理论知识同样重要。本文涵盖实践考核中需要掌握的关键要点，包括安全守则、器材使用、测量方法以及观察记录。掌握这些技能将帮助你在实验中取得高分，并为今后的科学学习打下基础。
1. Safety in the Chemistry Lab | 化学实验室安全
You must wear safety goggles at all times to protect your eyes from chemicals, heat and broken glass. Never remove them during an experiment, even if they feel uncomfortable.
你必须全程佩戴护目镜，以保护眼睛免受化学品、热量和破碎玻璃的伤害。即使佩戴不舒适，实验过程中也绝对不要摘下。
Do not eat, drink or chew gum in the laboratory. Chemical residues can contaminate food and cause serious harm if swallowed.
不要在实验室里饮食或嚼口香糖。化学残留物可能污染食物，误食会造成严重伤害。
Tie back long hair, secure loose clothing and remove any hanging jewellery. These can catch fire on a Bunsen burner or get trapped in equipment.
将长发束起、扎紧宽松衣物并取下悬挂的首饰。这些物品可能被本生灯引燃或被器材夹住。
Never run or play in the lab. Always walk carefully and keep your work area tidy to avoid spills and accidents.
禁止在实验室内奔跑或嬉戏。必须小心行走并保持工作台整洁，防止药品洒溅和事故发生。
Wash your hands thoroughly with soap and water after handling chemicals, even if you wore gloves. This prevents skin irritation and stops you from transferring harmful substances out of the lab.
接触化学品后，即使戴了手套，也要用肥皂和清水彻底洗手。这可以避免皮肤刺激，并防止将有害物质带出实验室。
2. Recognising Hazard Symbols | 识别危险标志
The corrosive symbol shows a test tube pouring liquid onto a hand and a surface. It warns that the substance can burn skin and damage materials. Common examples include strong acids and alkalis like hydrochloric acid and sodium hydroxide.
腐蚀性标志显示一支试管将液体倒在手和表面上。它警告该物质会灼伤皮肤并损坏材料。常见的例子包括强酸和强碱，如盐酸和氢氧化钠。
The flammable symbol is a flame. It tells you that the chemical catches fire easily near a heat source or spark. Ethanol and propanone are typical flammable liquids used in Year 7.
易燃标志是一团火焰。它提醒你该化学品靠近热源或火花时容易起火。乙醇和丙酮是Year 7实验中常见的易燃液体。
The toxic symbol (skull and crossbones) indicates that the substance can cause death or serious illness if it enters the body through swallowing, inhalation or skin contact. You would rarely handle such chemicals in Year 7, but you must still recognise the symbol.
有毒标志（骷髅与交叉骨）表示该物质如果进入体内——通过吞食、吸入或皮肤接触——可能导致死亡或严重疾病。Year 7实验中很少直接接触这类化学品，但你仍须认识该标志。
The harmful/irritant symbol features an exclamation mark. It warns of less severe hazards, such as skin redness, coughing or stinging eyes. Many household cleaning products carry this symbol.
有害/刺激性标志带有一个感叹号。它警告较为轻微的危险，例如皮肤发红、咳嗽或眼睛刺痛。许多家用清洁产品都带有这个标志。
In your practical assessment, you may be asked to match hazard symbols to their meanings or to suggest precautions like wearing gloves and working in a fume cupboard for hazardous substances.
在实践考核中，你可能会被要求将危险标志与其含义配对，或建议相应的防范措施，例如处理危险物质时佩戴手套并在通风橱中操作。
3. Common Laboratory Equipment and Measuring | 常用实验器材与测量
A beaker is a wide cylindrical glass container used for holding, mixing and heating liquids. It is not designed for accurate volume measurement despite the scale printed on the side.
烧杯是一种宽身圆柱形玻璃容器，用于盛放、混合和加热液体。尽管侧壁印有刻度，但它并非用于精确测量体积。
A measuring cylinder is tall and narrow, giving far more accurate liquid volume readings. You must place it on a flat surface and read the bottom of the meniscus at eye level to avoid parallax error.
量筒细高，能提供准确得多的液体体积读数。你必须将其放在水平台面上，并在视线水平处读取凹液面最低点，以避免视差错误。
A conical flask (Erlenmeyer flask) has a narrow neck and a wide base. It is useful for swirling liquids without spilling, often used in titrations at a later stage, but in Year 7 it is mainly used for mixing and heating.
锥形瓶（三角烧瓶）瓶颈窄小、底部宽阔。它适合旋转混合液体而不溅出，后期常用于滴定实验，但在Year 7主要用于混合与加热。
A test tube holds small amounts of substances for heating or observation. Always use a test tube holder when heating. Never point the open end at yourself or anyone else.
试管用于盛放少量物质进行加热或观察。加热时务必使用试管夹，并切勿将管口对着自己或他人。
An electronic balance measures mass in grams (g). Always zero the balance before placing anything on it. Record the mass immediately and use a weighing boat for powders to keep the pan clean.
电子天平以克（g）为单位测量质量。放上物品前务必归零。记录质量要迅速，并使用称量舟盛放粉末以保持秤盘清洁。
A thermometer is used to record temperature in degrees Celsius (°C). Never stir with a thermometer – it can break. Wait for the reading to stabilise before recording.
温度计用于记录温度，单位为摄氏度（°C）。切勿用温度计搅拌——它会折断。待读数稳定后再记录。
4. Using a Bunsen Burner Correctly | 正确使用本生灯
Before lighting the burner, check that the rubber tubing is securely attached and not cracked. Place the burner on a heat‑proof mat away from flammable materials.
点燃本生灯前，检查橡胶管是否连接牢固、有无裂纹。将灯放在耐热垫上，远离易燃物。
Close the air hole fully so the flame will be yellow and easy to see. Light a splint, then turn on the gas and hold the splint just above the chimney. The yellow flame is called the safety flame because it is visible and cooler, but it produces soot.
完全关闭气孔，使火焰呈黄色且易于看见。点燃引火条，然后打开煤气并将引火条置于灯管口上方。这种黄色火焰称为安全焰，因为它明显且温度较低，但会产生碳黑。
To obtain a hot blue flame for heating, slowly open the air hole. The flame becomes paler, noisier and hotter. The hottest part is the tip of the inner blue cone. You must be able to switch between the two flame types on demand in your assessment.
要得到加热用的高温蓝色火焰，缓慢打开气孔。火焰变得苍白、有响声且温度更高。最热的部分是内部蓝色锥体的尖端。在考核中，你必须能按要求转换这两种火焰。
When you have finished, immediately turn off the gas at the main tap. Do not touch the burner until it has cooled.
使用完毕后，立即关闭煤气总阀。在充分冷却前不要触碰本生灯。
5. Heating Substances Safely | 安全加热物质
When heating a liquid in a test tube, fill it no more than one‑third full. Hold the tube with a test tube holder at a 45‑degree angle, moving it gently back and forth through the flame to avoid sudden boiling (bumping).
在试管中加热液体时，液量不要超过三分之一。用试管夹夹住试管，保持约45度角，在火焰中轻轻来回移动，避免突然暴沸（ bumping）。
Always point the mouth of the test tube away from yourself and others. Hot liquid can shoot out violently if bumping occurs.
务必使试管口远离自己和他人。一旦发生暴沸，热液体会猛烈喷出。
If you are heating a beaker or conical flask over a Bunsen burner, place a tripod and gauze over the flame. The gauze spreads the heat evenly and supports the glassware. Never place glassware directly in the flame unless instructed.
如果要在本生灯上加热烧杯或锥形瓶，先把三脚架和石棉网放在火焰上方。石棉网能均匀传热并支撑玻璃器皿。除非得到指示，否则切勿将玻璃器皿直接置于火焰中。
To evaporate a solution and obtain solid crystals, use an evaporating dish on a tripod and gauze. Heat gently – do not evaporate to complete dryness, as the hot solid can spit. Stop heating when crystals begin to form, then leave the rest to evaporate slowly at room temperature.
要蒸发溶液获得固体晶体，使用蒸发皿放在三脚架和石棉网上。缓慢加热——不要蒸干，因为灼热的固体会飞溅。当晶体开始形成时停止加热，让其剩余部分在室温下缓慢蒸发。
Anti‑bumping granules (small pieces of porous porcelain) may be added to liquids before heating to prevent violent boiling and ensure smooth ebullition.
加热前可在液体中加入沸石（多孔瓷片），以防止剧烈沸腾，保证沸腾平稳。
6. Observing Chemical Changes | 观察化学变化
A chemical change produces new substances and is often accompanied by visible signs. You will be assessed on your ability to record these observations accurately, not just on knowing what should happen.
化学变化产生新物质，往往伴随可见的迹象。考核着重评价你准确记录这些观察结果的能力，而不仅仅是知道应该发生了什么。
A permanent colour change indicates a new substance has formed. For example, when blue copper(II) sulfate crystals are heated, they turn into a white powder, and water vapour is released. The symbol equation is:
永久的颜色变化表明有新物质生成。例如，加热蓝色硫酸铜晶体时，它们变为白色粉末并释放水蒸气。化学方程式为：
CuSO₄ · 5H₂O → CuSO₄ + 5H₂O
炫亮的蓝色硫酸铜晶体加热后变为白色无水硫酸铜粉末，这是一个典型的颜色变化反应，也是可逆反应的例子。
Effervescence (bubbles) shows a gas is being produced. Adding dilute hydrochloric acid to marble chips (calcium carbonate) gives off carbon dioxide gas. The limewater test is used to confirm CO₂: bubble the gas through limewater, and it turns cloudy or milky.
冒泡（放出气体）表明有气体生成。向大理石碎块（碳酸钙）中加入稀盐酸会释放二氧化碳。常用石灰水检验CO₂：将气体通入石灰水中，石灰水变浑浊或呈牛奶状。
CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O
碳酸钙与盐酸反应生成氯化钙、二氧化碳和水。石灰水变浑浊是因为生成了不溶的碳酸钙。
A precipitate forms when two clear solutions are mixed to produce an insoluble solid. For instance, mixing lead(II) nitrate and potassium iodide solutions creates a bright yellow precipitate of lead(II) iodide.
两种澄清溶液混合产生不溶性固体时叫作生成沉淀。例如，混合硝酸铅和碘化钾溶液会产生亮黄色的碘化铅沉淀。
Temperature change is another sign. Some reactions, like adding magnesium to acid, make the test tube feel hot (exothermic). Others, like dissolving ammonium nitrate in water, make the container feel cold (endothermic). You should measure the temperature before and after mixing to record the change precisely.
温度变化是另一个迹象。有些反应，如镁与酸的反应，会使试管发烫（放热反应）；而另一些反应，如硝酸铵溶于水，会使容器变冷（吸热反应）。你应该在混合前后测量温度，以准确记录变化。
7. Separation Techniques: Filtration and Evaporation | 分离技术：过滤与蒸发
Filtration separates an insoluble solid from a liquid. You will need a filter funnel, filter paper, a conical flask and the mixture. Fold the filter paper into a cone and place it in the funnel, moistening it slightly so it sticks.
过滤用于将不溶性固体从液体中分离。你需要准备过滤漏斗、滤纸、锥形瓶和混合物。把滤纸折叠成圆锥形放入漏斗，稍加湿润使其贴附。
Pour the mixture slowly along a glass rod into the funnel. The rod guides the stream and prevents splashing. The liquid that passes through (the filtrate) should be clear; the solid trapped on the paper is the residue. You must not let the liquid rise above the top edge of the filter paper, or unfiltered mixture will pass through.
将混合物沿玻璃棒缓慢倒入漏斗。玻璃棒能导流并防止飞溅。透过滤纸的液体（滤液）应是清澈的；留在滤纸上的固体是残渣。液面绝不能超过滤纸上沿，否则未过滤的混合物会直接流过。
Evaporation is used to obtain a soluble salt from a solution. Heat the solution in an evaporating dish on a tripod and gauze. As the water evaporates, the dissolved solid starts to crystallise. Stop heating when small crystals appear at the edge or when about half the water has boiled off. Allow the rest to cool and evaporate slowly – larger, purer crystals will form by slow crystallisation.
蒸发用于从溶液中获得可溶性盐。将溶液放在三脚架和石棉网上的蒸发皿中加热。水分蒸发时，溶解的固体开始结晶。当边缘出现细小晶体或大约一半的水蒸发掉时，停止加热。让其冷却并缓慢蒸发——缓慢结晶会形成更大、更纯的晶体。
In your assessment, you might be asked why we do not heat to total dryness. The answer is that remaining solid may spit out of the dish, causing burns or loss of product, and some crystals may decompose if overheated.
考核中可能会问为何不能完全蒸干。答案是剩余固体会迸溅出皿，导致烫伤或产物损失，而且一些晶体过热会分解。
8. Chromatography: Separating Coloured Mixtures | 色谱法：分离有色混合物
Paper chromatography separates mixtures of coloured compounds, such as the dyes in ink or food colouring. You draw a start line in pencil – never pen – because pencil graphite is insoluble and will not move with the solvent. If you use ink, it will run and ruin the separation.
纸色谱法用于分离有色化合物混合物，例如墨水或食用色素中的染料。你需要用铅笔画起点线——绝不能使用钢笔——因为铅笔石墨不溶于溶剂，不会随溶剂移动。如果使用墨水，墨水会扩散并破坏分离效果。
Place a small spot of the mixture on the pencil line. Lower the paper into a beaker with a shallow depth of water (or ethanol), ensuring the spot is above the solvent surface. The solvent travels up the paper, carrying the different dyes at different speeds, so they separate into several spots.
在铅笔线上点一小点混合物。将纸放入盛有少量水（或乙醇）的烧杯中，确保色点高于溶剂液面。溶剂沿纸上升，以不同速率带动各染料，从而使它们分离成多个色斑。
Remove the paper before the solvent front reaches the top and immediately mark the solvent front with a pencil. Each spot represents a
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