Year 8 AQA Chemistry: Case Study Practice | 八年级 AQA 化学：案例分析实战演练

📚 Year 8 AQA Chemistry: Case Study Practice | 八年级 AQA 化学：案例分析实战演练

Welcome to this case study practice article for Year 8 AQA Chemistry. Here we will explore real-world scenarios and practical problems to sharpen your understanding of key topics, from separating mixtures to energy changes and environmental chemistry. Each case study presents a situation, asks you to think like a scientist, and provides model answers in both English and Chinese. Use this resource to revise actively and build confidence for your tests.

欢迎阅读这篇八年级 AQA 化学案例分析实战演练文章。我们将通过真实场景和实际问题，加深你对混合物分离、能量变化以及环境化学等重点主题的理解。每个案例研究都会给出一种情境，让你像科学家一样思考，并提供中英对照的参考答案。利用这份资料进行积极复习，为考试树立信心。

1. Case Study: Separating Rock Salt | 案例研究：分离岩盐

A student collects a sample of rock salt, a mixture of salt (sodium chloride) and sand. She needs to obtain pure, dry salt crystals for a food preservation experiment. She decides to use dissolving, filtration, and evaporation.

一位学生采集了一份岩盐样品，这是盐（氯化钠）和沙子的混合物。她需要获得纯净、干燥的盐晶体用于食品保存实验。她决定采用溶解、过滤和蒸发的方法。

The student adds the rock salt to a beaker of warm water and stirs. The salt dissolves, but the sand does not.

学生将岩盐加入盛有温水的烧杯中并搅拌。盐溶解了，但沙子不溶解。
The mixture is poured through filter paper in a funnel. The sand remains as residue on the filter paper, while the salt solution (filtrate) passes through.

混合物通过漏斗中的滤纸过滤。沙子作为残渣留在滤纸上，而盐溶液（滤液）则穿过滤纸。
The clear salt solution is heated in an evaporating dish over a water bath. Water evaporates, leaving behind white salt crystals.

透明的盐溶液在蒸发皿中用水浴加热。水蒸发后，留下白色的盐晶体。

Why is filtration chosen here? Because sand is insoluble and can be separated from the soluble salt by physical means. The key is that salt dissolves in water, forming a solution, whereas sand does not change state.

为什么这里选择过滤？因为沙子不溶于水，可以通过物理方法将其与可溶性盐分离。关键在于盐能溶于水形成溶液，而沙子状态不变。

2. Case Study: Identifying Acids and Alkalis with Universal Indicator | 案例研究：用通用指示剂鉴别酸和碱

A laboratory technician needs to classify five colourless household solutions: lemon juice, soap water, distilled water, baking soda solution, and vinegar. She uses universal indicator solution and a pH colour chart.

一位实验室技术员需要对五种无色家用溶液分类：柠檬汁、肥皂水、蒸馏水、小苏打溶液和醋。她使用通用指示剂和pH比色卡。

Lemon juice turns the indicator red, indicating a strong acid with pH around 2.

柠檬汁使指示剂变红，表明是一种强酸，pH约为2。
Vinegar gives an orange colour, pH about 3, making it a weak acid.

醋呈现橙色，pH约3，属于弱酸。
Distilled water shows green, pH 7, neutral.

蒸馏水显示绿色，pH 7，中性。
Soap water turns blue-violet, showing it is alkaline with pH around 10-11.

肥皂水变成蓝紫色，说明它是碱性的，pH约10-11。
Baking soda solution gives a pale blue, pH about 9, a weak alkali.

小苏打溶液呈浅蓝色，pH约9，属于弱碱。

This case shows that everyday substances can be acidic, neutral, or alkaline, and the pH scale numerically measures the strength of acidity or alkalinity based on the concentration of H⁺ and OH⁻ ions.

这个案例表明日常物质可以是酸性、中性或碱性的，pH标度通过H⁺和OH⁻离子的浓度数值化地衡量酸碱强度。

3. Case Study: Reactivity of Metals and Displacement | 案例研究：金属活动性与置换反应

In a school laboratory, students test the reactivity of four metals: magnesium, zinc, iron, and copper. They place each metal into a solution of copper(II) sulfate and observe the changes.

在学校实验室，学生们测试四种金属的活动性：镁、锌、铁和铜。他们将每种金属放入硫酸铜(II)溶液中，观察变化。

Magnesium ribbon quickly darkens and a brown coat of copper forms on its surface; the blue solution fades and heat is released.

镁条迅速变暗，表面形成一层棕色的铜；蓝色溶液褪色并放出热量。
Zinc granules also displace copper, turning the solution colourless slowly and depositing a reddish-brown solid.

锌粒也能置换出铜，逐渐使溶液变无色，并沉积出红棕色固体。
Iron nail gets coated with copper, and the blue colour gradually disappears; the reaction is slower than with magnesium.

铁钉表面覆盖上铜，蓝色逐渐消失；反应比镁慢。
Copper foil shows no reaction with copper(II) sulfate because no displacement can occur; copper cannot displace itself.

铜箔与硫酸铜无反应，因为无法发生置换；铜不能置换自身。

This demonstrates the reactivity series: magnesium > zinc > iron > copper. A more reactive metal can displace a less reactive metal from its compound in solution.

这展示了金属活动性顺序：镁 > 锌 > 铁 > 铜。更活泼的金属能将较不活泼的金属从其化合物的溶液中置换出来。

4. Case Study: Acid Rain and Its Effects on Limestone Buildings | 案例研究：酸雨对石灰石建筑的影响

A famous cathedral built from limestone (calcium carbonate, CaCO₃) has been decaying faster in the last century. Environmental scientists suspect acid rain, which contains sulfuric acid (H₂SO₄) from industrial pollution.

一座由石灰石（碳酸钙，CaCO₃）建成的著名大教堂在上个世纪加速腐蚀。环境科学家怀疑是酸雨所致，酸雨中含有来自工业污染的硫酸（H₂SO₄）。

Limestone reacts with sulfuric acid in a neutralisation-like reaction, producing calcium sulfate, water, and carbon dioxide.

石灰石与硫酸发生类似中和的反应，生成硫酸钙、水和二氧化碳。

CaCO₃ + H₂SO₄ → CaSO₄ + H₂O + CO₂

Calcium sulfate is slightly soluble and can be washed away by rain, gradually eating away the stonework.

硫酸钙微溶，会被雨水冲走，逐渐侵蚀石雕。
Acid rain also corrodes metal statues and reduces the pH of soil and lakes, harming ecosystems. Reducing fossil fuel combustion and using scrubbers in power stations can help lower acid rain.

酸雨还会腐蚀金属雕像，降低土壤和湖泊的pH值，危害生态系统。减少化石燃料燃烧和在发电站中使用洗涤器有助于减少酸雨。

This case highlights how chemical reactions in the environment link to human activity and the importance of pollution control.

这个案例突显了环境中的化学反应如何与人类活动相关联，以及控制污染的重要性。

5. Case Study: Extracting Iron in a Blast Furnace | 案例研究：高炉炼铁

Iron is extracted from its ore, haematite (mainly iron(III) oxide, Fe₂O₃), in a blast furnace. Coke (carbon) and limestone are added, and hot air is blasted in. This case study examines the key reaction: reduction of iron oxide.

铁是从赤铁矿（主要是氧化铁，Fe₂O₃）中在高炉里提取的。加入焦炭（碳）和石灰石，并鼓入热空气。本案例研究关键反应：氧化铁的还原。

The carbon (coke) reacts with oxygen to form carbon dioxide, which then reacts with more carbon to form carbon monoxide.

碳（焦炭）与氧气反应生成二氧化碳，二氧化碳进一步与更多的碳反应生成一氧化碳。

C + O₂ → CO₂

CO₂ + C → 2CO

Carbon monoxide acts as a reducing agent, taking oxygen away from iron(III) oxide to leave molten iron.

一氧化碳作为还原剂，从氧化铁中夺走氧，留下熔融的铁。

Fe₂O₃ + 3CO → 2Fe + 3CO₂

Limestone decomposes and removes impurities like sand to form slag, which floats on the molten iron.

石灰石分解并去除沙子等杂质，形成炉渣，漂浮在铁水表面。
This industrial process uses redox principles and relies on the reactivity series: carbon is more reactive than iron and can displace it.

这个工业过程运用了氧化还原原理，并依赖金属活动性顺序：碳比铁活泼，能将其置换出来。

Understanding this case helps you link classroom theory to real-world metal extraction.

理解这个案例有助于你将课堂理论与现实世界的金属提取联系起来。

6. Case Study: Energy Transfer in Burning Foods | 案例研究：食物燃烧中的能量转移

Students use a simple calorimetry setup: a burning food sample (peanut) heats a known volume of water in a test tube. They measure temperature change to calculate energy released.

学生们使用简单的量热装置：燃烧的食物样品（花生）加热试管中已知体积的水。他们测量温度变化来计算释放的能量。

A peanut is speared on a mounted needle and ignited; the flame is immediately placed under a tube containing 20 cm³ of water.

花生穿在固定的针上并点燃；火焰马上放到装有20 cm³水的试管下方。
Initial water temperature is 22 °C; after the peanut stops burning, the highest temperature recorded is 52 °C. Temperature rise ΔT = 30 °C.

初始水温22 °C；花生停止燃烧后，记录到的最高温度为52 °C。温度上升ΔT = 30 °C。
Energy transferred (J) = mass of water (g) × specific heat capacity (4.2 J/g°C) × ΔT (°C). For 20 g of water, energy = 20 × 4.2 × 30 = 2520 J.

传递的能量（焦耳）= 水的质量（克）× 比热容（4.2 J/g°C）× ΔT (°C)。20克水，能量 = 20 × 4.2 × 30 = 2520 焦耳。
This experiment demonstrates that food contains stored chemical energy, which is released as heat during combustion. Errors arise from heat loss to the surroundings, so real values are higher.

该实验表明食物含有储存的化学能，燃烧时以热量形式释放。由于热量散失到环境中会产生误差，真实值更高。

This case reinforces energy changes in chemical reactions and the difference between exothermic and endothermic processes.

这个案例巩固了化学反应中的能量变化以及放热与吸热过程的区别。

7. Case Study: Paper Chromatography of Coloured Inks | 案例研究：彩色墨水的纸色谱分析

A forensic scientist finds a note written with a black pen at a crime scene. She uses paper chromatography to compare the ink with inks from three suspect pens. The chromatogram reveals different dye compositions.

一位法医科学家在犯罪现场发现了一张用黑色笔写的便条。她使用纸色谱法将该墨水与三支嫌疑笔的墨水进行比对。色谱图显示出不同的染料成分。

A spot of the crime-scene ink and spots from three reference pens are placed on a pencil line drawn on chromatography paper.

将犯罪现场墨水斑点和三支参考笔的斑点放在色谱纸上画的铅笔线上。
The paper is dipped in a solvent (water or ethanol) so the spots are above the surface. As solvent rises, dyes separate into coloured bands.

将纸浸入溶剂（水或乙醇），使斑点高于液面。溶剂上升时，染料分离成不同色带。
Pen A shows two dye bands: blue and yellow. Pen B shows only purple. Pen C shows blue and red. The crime ink matches Pen A, indicating it is the same brand.

笔A显示两种染料带：蓝色和黄色。笔B只有紫色。笔C显示蓝色和红色。犯罪墨水与笔A匹配，说明是同一品牌。
Different dyes have different solubilities and attractions to the paper, causing them to travel at different speeds. This is the principle of chromatography.

不同的染料具有不同的溶解度和对纸的吸附力，导致它们以不同速度移动。这就是色谱法的原理。

Paper chromatography is a physical separation method that can identify substances in a mixture without chemical change.

纸色谱法是一种物理分离方法，可以在不发生化学变化的情况下鉴别混合物中的物质。

8. Case Study: Desalination by Distillation | 案例研究：通过蒸馏进行海水淡化

A remote island has no fresh water source. Engineers design a solar-powered still to produce drinking water from seawater. The process relies on simple distillation and can be demonstrated in the lab.

一个偏远的岛屿没有淡水资源。工程师设计了一种太阳能蒸馏器，从海水中生产饮用水。该过程依赖简单蒸馏，可在实验室中演示。

Seawater is a mixture of water, dissolved salts, and minerals. Distillation separates water from the salts because water and salt have vastly different boiling points.

海水是水、溶解的盐和矿物质的混合物。蒸馏可将水与盐分离，因为水和盐的沸点相差极大。
In the lab, seawater is heated in a flask. Water boils at 100 °C, producing steam, while salts remain in the flask.

在实验室里，将海水在烧瓶中加热。水在100 °C时沸腾，产生蒸汽，而盐留在烧瓶中。
The steam passes through a condenser (a tube cooled by cold water), where it condenses back into liquid pure water (distillate).

蒸汽通过冷凝器（由冷水冷却的管子），在其中冷凝回液态纯水（蒸馏液）。
A thermometer at the top of the flask should show 100 °C during steady boiling, confirming pure water vapour.

烧瓶顶部的温度计在稳定沸腾时应显示100 °C，确认是纯水蒸汽。

Desalination is an energy-intensive but vital process for providing fresh water in coastal arid regions. It also models the water cycle, where evaporation and condensation naturally purify water.

海水淡化虽然能耗高，但对沿海干旱地区提供淡水至关重要。它也模拟了水循环，蒸发和冷凝自然净化水的过程。

9. Case Study: The Formation of Sedimentary Rocks | 案例研究：沉积岩的形成

Geologists study cliff faces and find layers of sedimentary rock containing fossils. They explain how limestone, sandstone, and chalk form over millions of years from sediments under pressure.

地质学家研究悬崖剖面，发现含有化石的沉积岩层。他们解释了石灰岩、砂岩和白垩如何在数百万年内由沉积物在压力下形成。

Sediments such as sand, mud, and shells are transported by rivers and settled in layers at the bottom of seas or lakes.

沙子、泥土和贝壳等沉积物被河流搬运，并在海底或湖底一层层沉积下来。
Over time, more layers bury the lower sediments, increasing pressure and squeezing out water. Minerals from groundwater crystallise and cement the particles together (lithification).

随着时间的推移，更多层覆盖下部沉积物，压力增大，挤出水份。地下水中的矿物质结晶并将颗粒胶结在一起（成岩作用）。
Limestone often forms from the compressed shells and skeletons of marine organisms, consisting mainly of CaCO₃. Fossils are preserved within the rock.

石灰岩通常由海洋生物的压缩贝壳和骨骼形成，主要成分是CaCO₃。化石保存在岩石内部。
The rock cycle links sedimentary rocks to metamorphic and igneous rocks through heating, burial, and melting.

岩石循环通过加热、埋藏和熔融将沉积岩与变质岩和火成岩联系起来。

Understanding how sedimentary rocks form helps explain Earth’s history and the composition of natural resources like building stone and fossil fuels.

了解沉积岩的形成方式有助于解释地球历史以及建筑材料（如石材）和化石燃料等自然资源的组成。

10. Case Study: Carbon Cycle and Climate Change | 案例研究：碳循环与气候变化

Data from ice cores show that carbon dioxide levels in the atmosphere have risen sharply since the Industrial Revolution. Year 8 students are asked to analyse how human activities disrupt the carbon cycle.

来自冰芯的数据显示，自工业革命以来，大气中的二氧化碳浓度急剧上升。要求八年级学生分析人类活动如何干扰碳循环。

In the natural carbon cycle, CO₂ is removed from the atmosphere by photosynthesis in plants and absorbed by oceans. It returns via respiration, decomposition, and volcanic eruptions.

在自然碳循环中，二氧化碳通过植物光合作用从大气中去除并被海洋吸收。它通过呼吸作用、分解和火山喷发返回大气。
Human activities such as burning fossil fuels (coal, oil, gas) and deforestation release extra CO₂, upsetting the balance.

燃烧化石燃料（煤、石油、天然气）和砍伐森林等人类活动释放了额外的二氧化碳，打破了平衡。
Increased CO₂ enhances the greenhouse effect, trapping more heat in the atmosphere and leading to global warming, melting ice caps, and extreme weather.

二氧化碳增加增强了温室效应，在大气中滞留更多热量，导致全球变暖、冰盖融化和极端天气。
Solutions include shifting to renewable energy, reforestation, and carbon capture. At a personal level, reducing energy consumption and recycling help cut carbon footprint.

解决方案包括转向可再生能源、植树造林和碳捕获。在个人层面，减少能源消耗和回收利用有助于减少碳足迹。

This case integrates chemical principles like combustion, oxidation, and the carbon cycle with real environmental challenges, showing the relevance of chemistry to global sustainability.

这个案例将燃烧、氧化和碳循环等化学原理与真实的环境挑战相结合，展示了化学与全球可持续发展的相关性。

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Year 8 AQA Chemistry: Case Study Practice | 八年级 AQA 化学：案例分析实战演练