HKDSE Chemistry Core
Section 5: Fossil Fuels and Carbon Compounds | 化石燃料與碳化合物
Billy Sir’s Smart Notes: Master Petroleum, Organic Compounds, Alkanes, Alkenes, and Polymers.
由資深導師 Billy Sir 編寫，助你極速掌握石油、有機化合物、烷烴、烯烴及聚合物。
1. Basics of Fossil Fuels & Fractional Distillation | 化石燃料基礎與分餾
Fossil fuels (coal, petroleum, and natural gas) are non-renewable energy sources formed from the remains of ancient plants and animals. 化石燃料（煤、石油和天然氣）是由古代動植物殘骸形成的不可再生能源。
🔬 Fractional Distillation of Petroleum | 石油的分餾
Petroleum is a complex mixture of hydrocarbons. It can be separated into useful fractions by fractional distillation based on differences in their boiling points. 石油是碳氫化合物的複雜混合物。可根據其沸點的差異，透過分餾將其分離成有用的餾份。
- Lighter fractions (Top of fractionating column): Smaller molecules, lower boiling points, highly volatile, flow easily, ignite easily. (e.g., Refinery gas, Petrol) (較輕的餾份在塔頂：分子較小，沸點較低，易揮發，易流動，易點燃。如煉油廠氣、汽油)
- Heavier fractions (Bottom of fractionating column): Larger molecules, higher boiling points, viscous, hard to ignite. (e.g., Fuel oil, Bitumen) (較重的餾份在塔底：分子較大，沸點較高，黏稠，難點燃。如燃油、瀝青)
2. Consequences of Using Fossil Fuels | 使用化石燃料的後果
Burning fossil fuels causes severe environmental problems: 燃燒化石燃料會導致嚴重的環境問題：
- Global Warming (全球暖化): Complete combustion releases \( \text{CO}_2 \), a greenhouse gas. (完全燃燒釋放二氧化碳，一種溫室氣體。)
- Acid Rain (酸雨): Impurities like sulfur burn to form \( \text{SO}_2 \), which dissolves in rain to form acid rain. (硫等雜質燃燒形成二氧化硫，溶於雨水形成酸雨。)
- Air Pollution (空氣污染): Incomplete combustion produces toxic Carbon Monoxide (\( \text{CO} \)) and soot (C). High temperatures in car engines cause \( \text{N}_2 \) and \( \text{O}_2 \) to react, forming nitrogen oxides (\( \text{NO}_x \)). (不完全燃燒產生有毒的一氧化碳和碳微粒。汽車引擎高溫令氮氣和氧氣反應形成氮氧化物。)
3. Introduction to Organic Compounds | 有機化合物簡介
Organic compounds are mainly composed of carbon atoms covalently bonded to hydrogen, oxygen, or other atoms. They are grouped into homologous series. 有機化合物主要由碳原子與氫、氧等原子以共價鍵結合而成。它們被歸類為同系列。
| Homologous Series (同系列) | General Formula (通式) | Functional Group (官能基) | Saturation (飽和度) |
|---|---|---|---|
| Alkanes 烷烴 |
\( \text{C}_n\text{H}_{2n+2} \) | None (Only C-C single bonds) 無 (只有 C-C 單鍵) |
Saturated 飽和 |
| Alkenes 烯烴 |
\( \text{C}_n\text{H}_{2n} \) | C=C double bond C=C 雙鍵 |
Unsaturated 不飽和 |
4. Reactions of Alkanes and Alkenes | 烷烴與烯烴的反應
⚠️ Exam Trap: Substitution vs. Addition | 考試陷阱：取代反應 vs 加成反應
Alkanes are generally unreactive but undergo Substitution Reactions with halogens under UV light. Alkenes are much more reactive and undergo Addition Reactions across the C=C double bond. 烷烴通常不活潑，但在紫外光下會與鹵素發生取代反應。烯烴較活潑，會在 C=C 雙鍵發生加成反應。
Alkanes (烷烴)
- Combustion (燃燒): \( \text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O} \)
- Substitution (取代反應): Requires UV light.
\( \text{CH}_4 + \text{Cl}_2 \xrightarrow{\text{UV light}} \text{CH}_3\text{Cl} + \text{HCl} \)
Alkenes (烯烴)
- Addition of Bromine (溴的加成反應): Used as a chemical test for unsaturation. The orange/brown bromine water turns colorless rapidly in the dark. (用作測試不飽和度的化學測試。橙/棕色的溴水在暗處會迅速變成無色。)
\( \text{C}_2\text{H}_4 + \text{Br}_2 \rightarrow \text{CH}_2\text{BrCH}_2\text{Br} \)
5. Addition Polymers | 加成聚合物
Addition polymerization is the process where many small unsaturated molecules (monomers) join together to form a very large molecule (polymer) without the loss of any small molecules. 加成聚合作用是指許多小的不飽和分子（單體）結合形成一個非常大的分子（聚合物），而沒有失去任何小分子的過程。
Ethene (Monomer) \( \rightarrow \) Poly(ethene) (Polymer)
乙烯 (單體) \( \rightarrow \) 聚乙烯 (聚合物)
- Properties: Plastics like poly(ethene) are durable, unreactive, and non-biodegradable, which leads to solid waste disposal problems. (特性：像聚乙烯這樣的塑膠耐用、不活潑且不可生物降解，這導致了固體廢物處理問題。)
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