Applications & Explore Online കാർബണിക രസതന്ത്രം

Hydrocarbons cook our food, move our autorickshaws, light our lamps, smooth our roads and keep moths out of our clothes. Every section below has a small animation or diagram, the chemistry at work and a sample exam question. Safety boxes cover the fuels (all flammable) and moth balls (toxic). The last section is about climate change in Kerala and what each of us can do. The page ends with a hub of links to explore online.

1. LPG cooking gas: butane in the kitchen

butane C₄H₁₀ · alkane · burns The red cylinder in a Kerala kitchen holds LPG എൽ.പി.ജി, liquefied petroleum gas. Its main component is butane ബ്യൂട്ടെയ്ൻ, C₄H₁₀, an alkane with 4 carbons, from the “gases” fraction (C₁–C₄) of petroleum. Under pressure inside the cylinder it is a liquid, so a lot of fuel fits in a small space. When you turn the knob, the pressure drops and the liquid turns to gas, flows to the stove and burns with a hot blue flame. go further 2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O + heat.

2. CNG autorickshaws and the LNG pipeline

natural gas = mainly methane CH₄ Natural gas പ്രകൃതിവാതകം is mostly methane, CH₄, the first alkane. Squeezed into strong cylinders at high pressure it becomes CNG സി.എൻ.ജി, compressed natural gas, which runs many autorickshaws and buses in Kochi. Turned into a liquid it is LNG എൽ.എൻ.ജി, liquefied natural gas, which takes up far less space and can be carried by ship. LNG arrives at the terminal at Puthuvype, Kochi, and GAIL supplies it as gas through pipelines in Kerala, to factories, CNG stations and kitchens (piped gas). Methane has only one carbon, so burning it gives less carbon pollution (less CO₂ and soot for the same heat): it is the more eco-friendly fuel. go further In practice LNG is made by cooling the gas to about −162 °C; CH₄ + 2O₂ → CO₂ + 2H₂O.

3. Petrol, diesel and the length of the chain

number of carbons → properties of the fuel At the petrol pump you can buy petrol (C₅–C₁₀) or diesel (C₁₆–C₂₀). They come from different heights of the same fractionating tower ഫ്രാക്ഷണേറ്റിങ് ടവർ at a refinery such as BPCL's Kochi refinery. Short chains boil at low temperatures and catch fire easily, so petrol suits the spark engines of scooters and cars; the longer diesel chains suit the diesel engines of buses, lorries and many autos. Your textbook's key idea: the number of carbon atoms and the structure of the chain decide the properties of a fuel. Slide along the chain to meet every fraction of Table 8.9.

4. Kerosene lamps

kerosene C₁₀–C₁₆ · domestic fuel Kerosene മണ്ണെണ്ണ (C₁₀–C₁₆) was the fuel of the chimney lamp and the wick stove in almost every Kerala home, and is still used during power cuts and by fishing boats. The cloth wick soaks up kerosene; the flame's heat turns it to vapour, and the vapour burns. Kerosene does not catch fire as easily as petrol, which is why it could be used in open lamps; with too little air it burns with a sooty, smoky flame.

5. Vaseline, grease and candles: the long chains

long chains → thick, waxy, high boiling Lower down the tower come chains too long to boil easily. Petroleum jelly (vaseline) and grease, C₂₀–C₅₀, are used as lubricants in bicycle chains and machines, and in cosmetics such as lip balm and skin cream. Paraffin wax (C₆₀–C₇₀ in Table 8.9) makes candles, boot polish, wax paper and tarpaulin. In a candle, the solid wax melts, the liquid wax climbs the wick, turns to vapour and burns – the same idea as the kerosene lamp, with a solid fuel.

6. Tarred roads: bitumen

bitumen – above C₇₀ The black, sticky residue left at the very bottom of the fractionating tower is bitumen (more than 70 carbons per molecule). Heated until it flows, it is mixed with crushed stone and spread on the road, then pressed by a road roller; as it cools it sets hard and binds the stones and keeps water out. That is the “tar” of our roads.

7. Moth balls: naphthalene

naphthalene C₁₀H₈ · aromatic The white balls kept in cupboards and with stored clothes are moth balls പാറ്റാഗുളിക. Many are made of naphthalene നാഫ്തലീൻ, C₁₀H₈: two benzene rings fused together, an aromatic hydrocarbon with a strong smell that keeps moths and insects away. It is obtained from coal tar. Over weeks the balls get smaller without leaving any liquid: the solid turns straight into vapour (it sublimes go further), which is why their smell fills the cupboard.

8. Plastics and medicines from petroleum go further

petrochemicals Not all petroleum is burnt. Small molecules such as ethene, CH₂=CH₂, made from petroleum fractions, are the starting materials for plastics. When the double bonds of thousands of ethene molecules open, the molecules join end to end into one very long chain: polythene, used for carry bags, milk packets and bottles. Benzene and other compounds from petroleum and coal tar are used to make medicines, dyes, perfumes and synthetic fibres. Because plastics are made to last, throwing them away pollutes our land and sea: reduce, reuse and recycle.

9. Coal in power stations – and why we burn less of it

coal: carbonisation · % carbon Coal കൽക്കരി formed from plants buried millions of years ago: heat and pressure, without air, slowly turned them into carbon – carbonisation കാർബണൈസേഷൻ. The longer and harder the process, the more carbon: peat 57 %, lignite 67 %, bituminous coal 83 %, anthracite 94 %. Much of India's electricity still comes from thermal power stations that burn coal: C + O₂ → CO₂. Every tonne of carbon burnt adds carbon dioxide to the air, along with smoke and ash. That is why the country is adding solar, wind and hydro power, and why saving electricity at home also cuts CO₂.

10. Climate change in Kerala – and what we can do

greenhouse gases trap infrared rays Sunlight warms the Earth; the warm Earth sends out infrared rays ഇൻഫ്രാറെഡ് രശ്മികൾ. CO₂, CH₄, N₂O and CFCs (the greenhouse gases ഹരിതഗൃഹവാതകങ്ങൾ) trap part of this heat. A little of this greenhouse effect ഹരിതഗൃഹപ്രഭാവം keeps Earth warm enough for life; the extra gases from burning fossil fuels and cutting forests trap more, and the average temperature rises: global warming. Kerala already feels it: the extreme rain and floods of August 2018, more very hot days, and the sea eating into the coast. The good news: each of us can help.

🌐 Explore online – resources hub

Everything in this guide works offline. The links below are extras: articles and simulations from trusted sources, grouped by topic. They need internet and open in a new tab, so you will not lose your place here. Ask a parent or teacher before you go online.

Organic chemistry and catenation

Hydrocarbons: alkanes, alkenes, alkynes

IUPAC naming

Ring compounds and aromatic hydrocarbons

Petroleum, coal and natural gas

Greenhouse effect and global warming