📚 Year 7 OCR Chemistry: Practical Skills and Experimental Techniques | Year 7 OCR 化学：实验技能与实践考核要点
In Year 7 OCR Chemistry, practical assessments focus on your ability to work safely in a laboratory, handle basic apparatus, make accurate observations, and record data systematically. This guide covers the essential skills you need to demonstrate, from lighting a Bunsen burner to writing a full lab report, helping you build confidence for every hands-on experiment.
在 Year 7 OCR 化学课程中，实践考核重点考察你在实验室安全操作、使用基本仪器、准确观察并系统记录数据的能力。本指南涵盖从点燃本生灯到撰写完整实验报告的所有必备技能，帮助你在每一次动手实验中建立信心。
1. Laboratory Safety Rules | 实验室安全规范
Always wear safety goggles to protect your eyes from splashes, fumes, or flying particles. Tie back long hair, tuck in ties or scarves, and avoid loose clothing that could catch fire or knock over equipment.
始终佩戴护目镜，防止液体飞溅、烟雾或飞散颗粒伤害眼睛。长发要扎起，领带或围巾要塞好，避免穿着宽松衣物，以防着火或碰倒仪器。
Never taste any chemicals, and do not eat or drink in the laboratory. Wash your hands after handling substances, even when you think they are harmless, and report all accidents or breakages to your teacher immediately.
绝对不要尝任何化学品，也不要在实验室吃喝。接触化学物质后要洗手，即便你认为它们无害。任何意外或破损都应立即向老师报告。
Know the location of the fire extinguisher, fire blanket, and eyewash station. In case of a chemical spill on skin, rinse with plenty of water for at least 10 minutes while calling for help.
熟知灭火器、灭火毯和洗眼器的位置。若皮肤沾染化学品，立即用大量水冲洗至少10分钟，并同时呼救。
2. Common Laboratory Apparatus | 常用实验仪器
A beaker is a wide cylindrical container used for holding, mixing, and heating liquids. It is not designed for precise volume measurements, so use it for rough work and when you need to pour solutions easily.
烧杯是一种宽口圆柱形容器，用于盛放、混合和加热液体。它并非为精确测量体积而设计，因此适合粗略操作和便于倾倒溶液的场合。
A conical flask, with its narrow neck, is perfect for swirling liquids without spilling, making it ideal for titrations or when you need to mix reagents by hand. A measuring cylinder gives you a much more accurate volume reading than a beaker, and you should always read the bottom of the meniscus at eye level.
锥形瓶颈部较窄，适合摇动液体而不溅出，非常适用于滴定或需要手动混合试剂的操作。量筒比烧杯能提供更精确的体积读数，你必须始终在视线水平处读取液面凹液面的最低点。
Other key items include a test tube for small-scale reactions, a test tube rack to hold tubes safely, a tripod and gauze to support containers during heating, and a heat-proof mat to protect the bench.
其他关键器材包括：用于少量反应的试管、用来安全放置试管的试管架、加热时支撑容器的三脚架和陶土网，以及保护台面的隔热垫。
3. Measuring and Recording | 测量与记录
For liquid volumes, always choose the most appropriate apparatus: a measuring cylinder for volumes over 10 cm³, a pipette for fixed small volumes, and a burette for precise additions. Record your measurements with the correct number of decimal places, always including the unit.
对于液体体积，始终选择最合适的仪器：量筒适用于10 cm³以上的体积，移液管用于固定的小体积，滴定管用于精确加液。记录测量值时应保留正确的小数位数，并始终包含单位。
When measuring temperature, use a thermometer with a suitable range and wait until the reading stabilises. In exothermic reactions the temperature rises, while in endothermic reactions it falls; note the highest or lowest point reached.
测量温度时，使用量程合适的温度计，待读数稳定后再记录。放热反应温度上升，吸热反应温度下降；要记录达到的最高或最低温度。
Always create a results table with clear headings that include the quantity and unit, e.g., 'Time (s)' and 'Temperature (°C)'. Draw the table before you start the experiment so you can fill in data as it is collected.
始终设计好结果表格，表头要清晰注明物理量和单位，例如“时间（s）”和“温度（°C）”。在实验开始前画好表格，以便边收集数据边填写。
4. Using a Bunsen Burner Safely | 本生灯的安全使用
Connect the rubber tubing to the gas tap securely and check for leaks. Close the air hole fully, light a splint, and hold it just above the chimney before turning on the gas. Always use a yellow safety flame when not actively heating, as it is highly visible and less likely to go unnoticed.
将橡胶管牢固地连接在煤气龙头上，检查是否漏气。将气孔完全关闭，点燃引火条，将其置于烟囱上方再打开煤气。不加热时始终使用黄色安全焰，因为它非常显眼，不易被忽视。
To obtain a roaring blue flame for heating, slowly open the air hole until the flame turns pale blue and a distinct inner cone appears. The hottest part of this flame is just above the tip of the inner cone. Never leave a lit Bunsen burner unattended, and turn off the gas at the tap immediately after use.
要得到加热用的蓝色强火，缓慢打开气孔直至火焰变为淡蓝色并出现清晰的内焰锥。火焰中最热的部分恰好在内焰锥尖端上方。切勿让点燃的本生灯无人看管，用后立即关闭煤气龙头。
5. Heating and Cooling Techniques | 加热与冷却技术
When heating a liquid in a test tube, use a test tube holder and point the open end away from yourself and others. Move the tube gently in and out of the flame to distribute heat evenly and prevent violent boiling that could eject hot liquid.
在试管中加热液体时，使用试管夹并将开口端远离自己和他人。轻轻地将试管在火焰中来回移动，使热量均匀分布，防止剧烈沸腾导致热液喷出。
To heat a beaker of water, place it on a tripod with a gauze mat, and never heat a beaker directly with a Bunsen burner without the gauze. For gentle evaporation, use a water bath: a beaker of boiling water under an evaporating dish, which gives indirect, steady heat.
加热烧杯中的水时，将其放在垫有陶土网的三脚架上，切勿直接用本生灯加热烧杯而不垫陶土网。若要温和蒸发，使用水浴：在蒸发皿下方放一烧杯沸水，提供间接恒定的热量。
Cooling can be achieved by placing the container in an ice-water bath. Record temperature changes every 30 seconds to observe the cooling curve, which helps identify whether heat loss is even or rapid initially.
可将容器放入冰水浴中实现冷却。每30秒记录一次温度变化来观察冷却曲线，这有助于判断热量散失是均匀还是前期更快。
6. Mixing, Dissolving, and Stirring | 混合、溶解与搅拌
When dissolving a solid in a solvent, break the solid into smaller pieces to increase surface area, which speeds up dissolution. Stir the mixture continuously with a glass rod; avoid using a thermometer as a stirring rod because it can snap.
将固体溶解在溶剂中时，把固体碾碎成更小的颗粒以增大表面积，从而加快溶解。用玻璃棒连续搅拌混合物；不要把温度计当搅拌棒使用，因为它可能折断。
For mixing two solutions, swirl the conical flask gently instead of shaking vigorously to minimise splashing. If the reaction produces a colour change or a precipitate, record the observation immediately, noting whether it appears instantly or over time.
混合两种溶液时，轻轻旋摇锥形瓶而不要剧烈震荡，以减少飞溅。如果反应发生颜色变化或生成沉淀，立即记录观察结果，并注明是瞬间出现还是逐渐形成。
7. Filtration and Evaporation | 过滤与蒸发
Filtration separates an insoluble solid from a liquid. Fold a filter paper into a cone, place it in a funnel, and moisten it with a little distilled water so it sticks to the funnel wall. Pour the mixture down a glass rod resting against the filter paper to prevent splashing and to guide the liquid.
过滤用于分离不溶性固体和液体。将滤纸折成圆锥形放入漏斗，用少量蒸馏水润湿使其紧贴漏斗壁。将玻璃棒抵在滤纸上，沿棒倾倒混合物，避免飞溅并引导液流。
The liquid that passes through is called the filtrate, and the solid left on the paper is the residue. If you need to recover the dissolved solid from the filtrate, use evaporation: pour the solution into an evaporating dish and heat gently over a water bath. Never heat to dryness with a direct flame, as the solid may spit or decompose.
穿过滤纸的液体叫滤液，留在纸上的固体叫残渣。如果需要从滤液中回收溶解的固体，使用蒸发：将溶液倒入蒸发皿，在水浴上温和加热。切勿用直接火焰加热至干，否则固体可能飞溅或分解。
8. Identifying Acids and Alkalis with Indicators | 用指示剂鉴别酸与碱
Litmus paper is the simplest indicator: blue litmus turns red in an acid, and red litmus turns blue in an alkali. Universal indicator solution or paper gives a range of colours across the pH scale, from red (strong acid) through green (neutral) to purple (strong alkali).
石蕊试纸是最简单的指示剂：蓝色石蕊遇酸变红，红色石蕊遇碱变蓝。通用指示剂溶液或试纸在整个pH范围内呈现不同颜色，从红色（强酸）穿过绿色（中性）到紫色（强碱）。
When testing a solution, add only 2-3 drops of universal indicator to a small sample in a test tube; never dip the indicator paper directly into the stock bottle. Match the colour obtained against the pH chart provided, and record the pH to the nearest whole number, for example, pH 4.
测试溶液时，在试管中的少量样品里只加2-3滴通用指示剂；切勿将指示剂试纸直接伸入原装瓶中。将得到的颜色与提供的pH色卡比对，记录最接近的整数pH值，例如pH 4。
9. Collecting Gases Safely | 安全收集气体
Some chemical reactions produce gases that you may need to collect. The method depends on the gas's properties: for a gas that is denser than air, such as carbon dioxide, you can use downward delivery or a gas syringe. For a gas less dense than air, like hydrogen, use upward delivery.
某些化学反应会产生需要收集的气体。收集方法取决于气体性质：比空气重的气体，例如二氧化碳，可用向下排空气法或气密注射器收集；比空气轻的气体，如氢气，则用向上排空气法采集。
When collecting a gas over water, fill a trough and a measuring cylinder with water, invert the cylinder, and direct the delivery tube beneath its mouth. The gas displaces the water, and you can read the collected volume directly. Always test for hydrogen with a lit splint – it burns with a squeaky pop – and test for carbon dioxide by bubbling the gas through limewater, which turns milky.
使用排水集气法时，将水槽量筒装满水并倒置，将导气管口伸入量筒口下方。气体会将水排出，你便可直接读出收集到的体积。检测氢气时，用点燃的引火条靠近——氢气会燃烧并发出噗的一声；检测二氧化碳时，将气体通入石灰水，石灰水会变浑浊。
10. Writing a Scientific Lab Report | 撰写科学实验报告
A complete lab report includes a title, an aim stating what you want to investigate, a hypothesis (a predicted answer based on science), a list of apparatus and chemicals, a numbered step-by-step method, results in tables and graphs, a conclusion, and an evaluation.
一份完整的实验报告包括：标题、说明探究目的的“目标”、基于科学原理的预测“假设”、仪器和化学品清单、编号的分步“方法”、以表格和图表呈现的“结果”，以及“结论”和“评估”。
In your conclusion, state whether your results support the hypothesis, quote specific data to back up your statement, and explain the science behind the outcome. In the evaluation, comment on the reliability of the data, identify any anomalous points, and suggest improvements to the method, such as using more precise measuring instruments or repeating trials.
在结论中，陈述结果是否支持假设，引用具体数据来支持你的陈述，并解释结果背后的科学原理。在评估中，评价数据的可靠性，指出任何异常数据点，并提出方法改进建议，例如使用更精确的测量仪器或增加重复试验次数。
11. Identifying Variables: Independent, Dependent, and Control | 识别变量：自变量、因变量与控制变量
Every experiment involves variables. The independent variable is the one you deliberately change, such as the temperature of water or the mass of a solute. The dependent variable is the one you measure, for example the time taken for a tablet to dissolve.
每个实验都涉及变量。自变量是你主动改变的变量，例如水的温度或溶质的质量。因变量是你测量的量，例如药片溶解所需的时间。
Control variables are the factors you must keep the same to make sure that any effect on the dependent variable is caused only by the independent variable. In a dissolving experiment, control variables could include the volume of water, the type of solute, and the stirring speed.
控制变量是必须保持不变的因素，以确保对因变量的影响仅来自自变量的变化。在溶解实验中，控制变量可能包括水的体积、溶质的种类和搅拌速度。
Before starting, write down a clear list of control variables and how you intend to maintain them. When plotting a graph, the independent variable always goes on the x‑axis (horizontal) and the dependent variable on the y‑axis (vertical), with both axes labelled and units shown.
实验开始前，写下清晰的控制变量清单以及你将如何保持它们不变。绘制图表时，自变量永远放在x轴（横轴），因变量放在y轴（纵轴），两个轴都要标注名称和单位。
12. Accuracy, Precision, and Common Errors | 准确度、精密度与常见误差
Accuracy refers to how close a measured value is to the true value. Precision describes how close repeated measurements are to each other. You can have precise results that are not accurate, for example if your thermometer is consistently reading 2 °C too high.
准确度指测量值接近真实值的程度。精密度描述重复测量值彼此之间的接近程度。你有可能得到精密但不准确的结果，比如你的温度计恒定偏高 2 °C。
Common errors include parallax error when reading a measuring cylinder from an angle rather than at eye level; zero error when the instrument does not read zero before use; and procedural errors such as losing product during transfer. To minimise random errors, repeat each measurement three times and calculate the mean.
常见误差包括：从斜上方而非视线水平处读取量筒时产生的视差；仪器使用前未归零的零位误差；以及转移过程中损失产物等操作误差。为减少随机误差，重复测量三次并计算平均值。
Published by TutorHao | Chemistry Revision Series | aleveler.com
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