1 / 36

Chapter 23 Fossil Fuels

Chapter 23 Fossil Fuels. 23.1 Fossil fuels as a major energy source. 23.2 Coal. 23.3 Petroleum and natural gas. 23.4 Refining petroleum. CONTENTS OF CHAPTER 23. 23.1 FOSSIL FUELS AS A MAJOR ENERGY SOURCE ENERGY AND FUEL An important way of obtaining energy is to burn fuels.

tilden
Download Presentation

Chapter 23 Fossil Fuels

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 23 Fossil Fuels 23.1Fossil fuels as a major energy source 23.2Coal 23.3Petroleum and natural gas 23.4Refining petroleum CONTENTS OF CHAPTER 23

  2. 23.1 FOSSIL FUELS AS A MAJOR ENERGY SOURCE ENERGY AND FUEL An important way of obtaining energy is to burn fuels. 23.1 FOSSIL FUELS AS A MAJOR ENERGY SOURCE

  3. Figure 23.1 Burning fuels to provide energy. 23.1 FOSSIL FUELS AS A MAJOR ENERGY SOURCE

  4. A FUEL is a substance which is burnt to produce heat. At present, the commonest fuels are fossil fuels. WHAT FOSSIL FUELS ARE Coal, petroleum and natural gas are collectively called fossil fuels. They are so called because they were formed from the remains of plants and animals that lived hundreds of million years ago. Different fossil fuels have different properties. Yet they have one thing in common — they all contain hydrocarbons. (Hydrocarbons are compounds containing hydrogen and carbon only.) 23.1 FOSSIL FUELS AS A MAJOR ENERGY SOURCE

  5. 23.2 COAL The most abundant fossil fuel is coal. Coal is a black solid, usually quite hard. It consists of 65% – 95% carbon, together with hydrocarbons and some other compounds. Figure 23.3 Coal is a black solid consisting mainly of carbon. Its composition varies with the type of coal. 23.2 COAL

  6. ORIGIN OF COAL Coal was formed from the remains of plants that grew in swamps 250 million years ago. Due to movements of the Earth’s crust, the plant remains were deeply buried under layers of mud and sand. Under high pressure and temperature, the decaying plants gradually turned into coal. 23.2 COAL

  7. Figure 23.4 Plants that lived 250 million years ago were buried and turned into coal that we burn today. 23.2 COAL

  8. Figure 23.5 The formation of coal. 23.2 COAL

  9. USING COAL About two-thirds of the coal mined today is burnt in power stations to generate electricity. Coal can be changed to a number of useful substances by a special process. 23.2 COAL

  10. Figure 23.8 The Lamma power station in Hong Kong burns coal to generate electricity. The picture shows coal being unloaded from a ship. 23.2 COAL

  11. 23.3 PETROLEUM AND NATURAL GAS Petroleum is a smelly oily liquid, usually quite thick; its colour ranges from greenish brown to black, depending on where it is obtained. Petroleum is a complex mixture consisting mainly of hydrocarbons. Natural gas is also a mixture mainly of hydrocarbons. It consists chiefly of methane CH4, with small amounts of ethane C2H6, propane C3H8 and butane C4H10. 23.3 PETROLEUM AND NATURAL GAS

  12. Figure 23.9 A sample of crude oil. 23.3 PETROLEUM AND NATURAL GAS

  13. ORIGIN OF PETROLEUM AND NATURAL GAS Petroleum and natural gas were formed from very small sea animals and plants (e.g. planktons) that lived hundreds of million years ago. 23.3 PETROLEUM AND NATURAL GAS

  14. Figure 23.10 Planktons are very small sea organisms. 23.3 PETROLEUM AND NATURAL GAS

  15. Figure 23.11 The oil story. 23.3 PETROLEUM AND NATURAL GAS

  16. A23.1 This is due to the movements of the Earth’s crust. USING PETROLEUM AND NATURAL GAS Petroleum is not burnt directly to supply energy. In fact, petroleum must be treated or refined first. The process of separating hydrocarbons in petroleum into several parts (fractions) is called the refining of petroleum. Unlike petroleum, most natural gas is burnt directly as a fuel. It burns with a clean blue flame, causing little pollution. 23.3 PETROLEUM AND NATURAL GAS

  17. Figure 23.16 Natural gas burns with a clean blue flame. 23.3 PETROLEUM AND NATURAL GAS

  18. natural gas 25% petroleum 38% coal 21% others 16% Uses of petroleum At present, petroleum supplies about 40% of the world’s energy needs. Figure 23.17 Contribution of various energy sources to the world’s energy needs. 23.3 PETROLEUM AND NATURAL GAS

  19. 23.3 PETROLEUM AND NATURAL GAS

  20. Figure 23.18 Uses of petroleum. 23.3 PETROLEUM AND NATURAL GAS

  21. A23.2 Drugs (e.g. Panadol), soapless detergents, plastic items (e.g. electrical socket), insecticides etc. (Many answers are possible.) Petroleum resource is running out Petroleum resource is limited and non-renewable. 23.3 PETROLEUM AND NATURAL GAS

  22. 23.4 REFINING PETROLEUM WHAT IS OIL REFINING? In oil refining, the complex mixture of hydrocarbons is separated (by fractional distillation) into less complex mixtures which are useful. Fractional distillation can be used because the hydrocarbons have different boiling points. In general, a hydrocarbon with larger molecules has a higher boiling point. This is because van der Waals’ forces are greater between larger molecules. These parts (simpler mixtures) are called fractions. 23.4 REFINING PETROLEUM

  23. Figure 23.19 Before and after refining of petroleum: (a) Petroleum is a complex mixture, consisting of hundreds of hydrocarbons. (b) A petroleum fraction is still a mixture, but it is a mixture simpler than petroleum. 23.4 REFINING PETROLEUM

  24. An OIL FRACTION is a mixture of hydrocarbons of similar boiling points and other properties. THE REFINING PROCESS In an oil refinery, petroleum is first heated in a furnace to about 400oC. The hot oil, now partly liquid and partly vapour, is pumped into the bottom of a tall tower called fractionating tower. 23.4 REFINING PETROLEUM

  25. Figure 23.20 Fractionating towers in an oil refinery. (Each tower is about 30 meters high.) 23.4 REFINING PETROLEUM

  26. A typical fractional distillation of petroleum. 23.4 REFINING PETROLEUM

  27. The heavy fractions (with high boiling point ranges) condense in the lower (hotter) compartments. The lighter fractions (with lower boiling point ranges) condense in the higher (cooler) compartments. RELATIONSHIP BETWEEN BOILING POINT RANGE AND NUMBER OF CARBON ATOMS IN HYDROCARBONS 23.4 REFINING PETROLEUM

  28. Figure 23.23 The petrol fraction consists of C5 – C10 hydrocarbon molecules. An oil fraction consisting of hydrocarbon molecules with more carbon atoms has a higher boiling point range. FRACTIONAL DISTILLATION OF CRUDE OIL IN THE LABORATORY 23.4 REFINING PETROLEUM

  29. 0 – 360oC thermometer clamp short rubber connecting tubing bent delivery tube rocksil soaked with crude oil small test tube water heat oil fraction Figure 23.24 Fractional distillation of crude oil in the laboratory. 23.4 REFINING PETROLEUM

  30. Fractional distillation of crude oil in the laboratory. 23.4 REFINING PETROLEUM

  31. 23.4 REFINING PETROLEUM

  32. An oil fraction with a higher boiling point range has a darker colour and is more viscous; it is less volatile, less flammable and burns less completely. A23.3 There is physical separation but no chemical decomposition. A23.4 Industrial refining, different, same, fractions, laboratory, different, in turn 23.4 REFINING PETROLEUM

  33. Activity 4 Some examples are: (1) Plastics There are many useful plastics. The commonest plastic is polythene, made from ethene. Ethene is obtained by cracking naphtha or gas oil. (2) Alcohol Ethanol can be manufactured from ethene. (3) Detergents Synthetic detergents are made from petroleum products. (4) Medicines and insecticides Many of these are made from substances obtained from petroleum. 23.4 REFINING PETROLEUM

  34. SUMMARY 1. Coal, petroleum and natural gas arefossil fuels. 2. Coal was formed from the remains of plants that lived 250 million years ago. Petroleum and natural gas were formed from the remains of very small sea animals and plants that lived hundreds of million years ago. SUMMARY

  35. 3. Petroleum has great economic importance. Petroleum-based fuels are burnt to provide heat and electricity for homes and industries. Petroleum also provides the starting chemical materials for the manufacture of a variety of important products. However, petroleum resource is limited and non-renewable. 4. Petroleum is a complex mixture mainly of hydrocarbons. Hydrocarbons are compounds containing hydrogen and carbon only. 5. Inrefining, petroleum is separated into several useful parts(fractions) by fractional distillation. This works because different hydrocarbons have different boiling points. SUMMARY

  36. 6. Each petroleum fraction has its particular uses. Refer to Figure 23.21 for the major uses of the various fractions. 7. A small-scale refining of crude oil can also be performed in the laboratory by fractional distillation. 8. As the number of carbon atoms in the molecules of an oil fraction increases, the properties of the fraction change as follows:  Boiling point range increases  Volatility decreases  Colour darkens  Viscosity increases  Flammability decreases  Flame (on burning) becomes darker and sootier SUMMARY

More Related