📚 Investigating Fuels | 探究燃料
Fuels are substances that release useful heat energy when they burn. In KS3 chemistry, investigating fuels means exploring what fuels are made of, how they burn, what products they form, and how we can compare the amount of energy different fuels release. This article guides you through the key ideas, common school experiments, and safety points you need to know.
燃料是燃烧时释放有用热能的物质。在 KS3 化学中，探究燃料意味着研究燃料由什么组成、它们如何燃烧、生成什么产物，以及我们如何比较不同燃料释放的能量。本文将带你梳理关键概念、常见课堂实验和安全要点。
1. What is a fuel? | 什么是燃料？
A fuel is any substance that stores energy in a chemical form and can release that energy as heat or light when it burns. Most fuels contain carbon and hydrogen, so they are often called hydrocarbons. During burning, stored chemical energy is transferred to the surroundings as thermal energy.
燃料是任何以化学形式储存能量，并在燃烧时以热或光的形式释放能量的物质。大多数燃料含有碳和氢，因此常被称为碳氢化合物。燃烧时，储存的化学能转化为释放到周围环境中的热能。
For a substance to be useful as a fuel, it must be easy to ignite, release a large amount of energy per gram, and be reasonably safe to store and transport. Wood, coal, petrol, and natural gas all meet these conditions in different ways.
一种物质要成为有用的燃料，它必须容易点燃，每克释放大量能量，并且储存和运输相对安全。木材、煤、汽油和天然气都以不同方式满足这些条件。
2. Common fuels and their uses | 常见燃料及其用途
Common fuels include wood, coal, natural gas, petrol, diesel, kerosene, and hydrogen. Each fuel has different properties that make it suitable for different jobs. For example, petrol is used in car engines because it evaporates easily and burns smoothly, while coal is used in some power stations because it is cheap and can produce a steady heat output.
常见燃料包括木材、煤、天然气、汽油、柴油、煤油和氢气。每种燃料都有不同的性质，使其适合不同的用途。例如，汽油用于汽车发动机，因为它容易蒸发且燃烧平稳；而煤用于一些发电站，因为它价格低廉并能稳定地产生热量。
| Fuel | 燃料 | State at room temperature | 室温状态 | Typical use | 典型用途 |
|---|---|---|
| Natural gas | 天然气 | Gas | 气体 | Heating and cooking | 供暖和烹饪 |
| Petrol | 汽油 | Liquid | 液体 | Car engines | 汽车发动机 |
| Coal | 煤 | Solid | 固体 | Power stations | 发电站 |
| Hydrogen | 氢气 | Gas | 气体 | Rocket fuel and fuel cells | 火箭燃料和燃料电池 |
3. Fossil fuels: coal, oil and natural gas | 化石燃料：煤、石油和天然气
Coal, oil and natural gas are called fossil fuels because they formed from the remains of dead plants and animals over millions of years. These fuels are non-renewable: once they are used, they cannot be replaced within a human lifetime. Fossil fuels are the main energy source for electricity generation, transport, and heating worldwide.
煤、石油和天然气被称为化石燃料，因为它们是由死去的动植物遗体经过数百万年形成的。这些燃料是不可再生的：一旦使用，在人的一生中就无法得到补充。化石燃料是全球发电、运输和供暖的主要能源。
Coal is mostly carbon. Crude oil is a mixture of many hydrocarbon compounds. Natural gas is mainly methane, CH₄. Because they all contain carbon, burning them releases carbon dioxide into the atmosphere.
煤的主要成分是碳。原油是多种碳氢化合物的混合物。天然气的主要成分是甲烷 CH₄。由于它们都含有碳，燃烧时都会向大气中释放二氧化碳。
4. Burning fuels: combustion | 燃烧燃料：燃烧反应
Combustion is a chemical reaction in which a fuel reacts with oxygen. When a fuel burns completely in a good supply of oxygen, it produces carbon dioxide and water. This is an exothermic reaction, which means it transfers energy to the surroundings, usually making them hotter.
燃烧是燃料与氧气发生的一种化学反应。当燃料在充足的氧气供应下完全燃烧时，会生成二氧化碳和水。这是一种放热反应，也就是说它会向周围环境传递能量，通常使周围温度升高。
The general word equation for the complete combustion of a hydrocarbon is:
碳氢化合物完全燃烧的通用文字方程式为：
hydrocarbon fuel + oxygen → carbon dioxide + water
For methane, the main gas in natural gas, the symbol equation is:
对于天然气中的主要气体甲烷，符号方程式为：
CH₄ + 2O₂ → CO₂ + 2H₂O
5. Products of combustion | 燃烧产物
Complete combustion of a hydrocarbon produces carbon dioxide and water vapour. If the oxygen supply is limited, incomplete combustion can occur, producing carbon monoxide or carbon particles, which appear as soot. Carbon monoxide is a toxic gas, so good ventilation is essential when burning fuels indoors.
碳氢化合物完全燃烧会生成二氧化碳和水蒸气。如果氧气供应不足，就会发生不完全燃烧，生成一氧化碳或碳颗粒，即烟灰。一氧化碳是一种有毒气体，因此在室内燃烧燃料时必须保持良好通风。
In the school laboratory, you can test the products of burning a candle or a small fuel burner. Water vapour can be collected as condensation on a cold surface, and carbon dioxide can be tested with limewater.
在学校实验室中，你可以检验蜡烛或小型燃料燃烧器燃烧的产物。水蒸气可以在冷的表面上凝结收集，二氧化碳可以用石灰水检验。
6. Testing for carbon dioxide and water | 检验二氧化碳和水
To test for water, hold a cold, dry test tube or beaker near the flame. If water is produced, colourless droplets condense on the cold surface. To test for carbon dioxide, bubble the gas through limewater. If carbon dioxide is present, the limewater turns milky or cloudy because insoluble calcium carbonate forms.
要检验水，可将一个冷而干燥的试管或烧杯靠近火焰。如果生成了水，无色的液滴会在冷表面上凝结。要检验二氧化碳，可将气体通入石灰水中。如果存在二氧化碳，石灰水会变浑浊或呈乳白色，因为生成了不溶性的碳酸钙。
| Test | 检验方法 | Positive result | 阳性结果 | Explanation | 解释 |
|---|---|---|
| Water: cold surface | 水：冷表面 | Colourless liquid droplets appear | 出现无色液滴 | Water vapour condenses | 水蒸气凝结 |
| Carbon dioxide: limewater | 二氧化碳：石灰水 | Turns milky or cloudy | 变浑浊或乳白色 | CO₂ reacts with calcium hydroxide forming calcium carbonate | CO₂ 与氢氧化钙反应生成碳酸钙 |
7. Energy from fuels | 燃料释放的能量
Different fuels release different amounts of energy when they burn. We can compare fuels by measuring how much the temperature of a fixed amount of water rises when a known mass of fuel is burned. The greater the temperature rise, the more energy the fuel has transferred to the water.
不同燃料燃烧时释放的能量不同。我们可以通过燃烧已知质量的燃料，测量固定质量的水温度升高了多少，来比较燃料。温度升高越多，说明燃料传递给水的能量越多。
A simple way to calculate the energy transferred to water is to use the equation:
计算传递给水的能量的一种简单方法是使用以下公式：
energy transferred (J) = mass of water (g) × 4.2 × temperature rise (°C)
This equation assumes that all the heat from the burning fuel goes into the water. In practice, some heat is always lost to the air and to the container.
这个公式假设燃料燃烧产生的所有热量都进入水中。实际上，总有一部分热量散失到空气和容器中。
8. Comparing fuels: a fair test | 比较燃料：公平测试
To compare fuels fairly, only the type of fuel should change. Keep the same volume of water, same starting temperature, same height of the burner, same container, and same burning time. Measure the final temperature after the fuel has been burned. Record results in a table and repeat each test to spot anomalies.
为了公平地比较燃料，只能改变燃料的种类。保持相同的水量、相同的起始温度、相同燃烧器高度、相同容器和相同的燃烧时间。燃料燃烧后测量最终温度。将结果记录在表格中，并重复每次实验以发现异常值。
| Variable | 变量 | What it means | 含义 | Example | 示例 |
|---|---|---|
| Independent variable | 自变量 | The thing you change | 你改变的量 | Type of fuel | 燃料种类 |
| Dependent variable | 因变量 | The thing you measure | 你测量的量 | Temperature rise of water | 水温升高 |
| Control variables | 控制变量 | The things you keep the same | 你保持不变的量 | Volume of water, starting temperature, distance from flame | 水量、起始温度、与火焰的距离 |
9. Renewable and non-renewable fuels | 可再生与不可再生燃料
Renewable fuels can be replaced quickly or continuously, such as wood, bioethanol, and hydrogen produced from renewable electricity. Non-renewable fuels, such as coal, oil and natural gas, take millions of years to form and are being used up much faster than they are made.
可再生燃料可以快速或持续地得到补充，例如木材、生物乙醇以及由可再生电力生产的氢气。不可再生燃料，如煤、石油和天然气，需要数百万年才能形成，并且其使用速度远快于生成速度。
Biofuels are made from plants or waste. They are often described as carbon neutral because the plants absorbed carbon dioxide while growing. However, growing biofuel crops can use land that might otherwise grow food.
生物燃料由植物或废弃物制成。它们通常被描述为碳中性，因为植物在生长过程中吸收了二氧化碳。然而，种植生物燃料作物可能占用本可用于种植粮食的土地。
10. Safety in fuel investigations | 燃料实验安全
Fuels are flammable, so safety is very important. Always wear eye protection, tie back long hair, and keep fuels away from open flames except in the controlled burner. Use small amounts of liquid fuels in a metal or ceramic container. If a fire starts, tell the teacher immediately and use a fire blanket or extinguisher only if trained.
燃料是易燃的，因此安全非常重要。始终佩戴护目镜，把长发扎起来，并将燃料远离明火，除非是在受控的燃烧器中。使用少量液体燃料，并放在金属或陶瓷容器中。如果发生火灾，立即告诉老师，只有经过培训才能使用灭火毯或灭火器。
Never pour extra fuel onto a flame, and never leave a lit burner unattended. Make sure the laboratory is ventilated so toxic gases such as carbon monoxide do not build up.
切勿向火焰上额外倾倒燃料，切勿让点燃的燃烧器无人看管。确保实验室通风良好，以免一氧化碳等有毒气体积聚。
11. Fuels and the environment | 燃料与环境
Burning fossil fuels releases carbon dioxide, a greenhouse gas that contributes to climate change. It also releases sulfur dioxide and nitrogen oxides, which can cause acid rain. Using cleaner fuels and improving efficiency can reduce these harmful effects.
燃烧化石燃料会释放二氧化碳，这是一种导致气候变化的温室气体。它还会释放二氧化硫和氮氧化物，这些物质会导致酸雨。使用更清洁的燃料和提高效率可以减少这些有害影响。
Scientists and engineers are developing low-carbon fuels such as hydrogen and biofuels. Hydrogen burns to produce only water, but it is difficult to store and produce cheaply.
科学家和工程师正在开发氢和生物燃料等低碳燃料。氢气燃烧只生成水，但难以储存且生产成本较高。
2H₂ + O₂ → 2H₂O
12. Summary and revision checklist | 总结与复习清单
You should now be able to define a fuel, describe combustion, state the products of complete burning, explain how to test for water and carbon dioxide, compare fuels fairly, and discuss renewable and non-renewable fuels. Practise writing word equations and drawing labelled diagrams of the temperature-rise experiment.
现在你应该能够定义燃料，描述燃烧，说出完全燃烧的产物，解释如何检验水和二氧化碳，公平地比较燃料，并讨论可再生和不可再生燃料。练习书写文字方程式，并画出温度升高实验的标注示意图。
- Define a fuel and give examples | 定义燃料并举例
- Write the word equation for complete combustion | 书写完全燃烧的文字方程式
- Describe the limewater test for carbon dioxide | 描述检验二氧化碳的石灰水试验
- Identify independent, dependent and control variables | 识别自变量、因变量和控制变量
- Explain the difference between renewable and non-renewable fuels | 解释可再生与不可再生燃料的区别
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