Class-8 science Chapter-2 coal and petroleum
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- 2. 2 STUDY MATERIAL CLASS - VIII SCIENCE (CHEMISTRY) COAL AND PETROLEUM
- 3. 3 COAL AND PETROLEUM Resources supplied by nature are called natural resources. The sun, air, water, soil, trees and forests, wildlife, coal, petroleum, natural gas and minerals are all natural resources. Natural resources are classified as renewable and non-renewable resources. Renewable resources: Renewable resources are those that are present in unlimited quantity in nature or those that will replace themselves over time.These resources are not likely to be exhausted by human activities. As they are unlimited, they are also called inexhaustible resources. Example: Air, water Non-renewable resources: Non-renewable resources are those that are limited in nature and will not replace themselves. They can be exhausted by human activities. As they are limited, they are also called exhaustible resources. Example: Coal, petroleum and natural gas are exhaustible fossil fuels, They cannot be prepared in the laboratory. It takes millions of years for dead organisms to get converted into these fuels. Studies show that the known reserves of these fuels are fast depleting. Effects of using fuels: Burning of these fuels is also a major cause for air pollution and along with cutting down of trees, is contributing to global warming. Conservation of natural resources: Natural resources need to be conserved and this can be done by conserving energy. The Petroleum Conservation Research Association (PCRA) of India has some tips for people on how to save petrol/ diesel while driving: • Drive vehicles at a constant and moderate speed. • While waiting or at a traffic junction, switch off the engine. • Ensure correct tyre pressure. • Ensure regular maintenance checks of the vehicle. Tips for conserving energy at home and school: • Switch off lights and electrical appliances when not in use. • Turn off air conditioning when leaving the room.
- 4. 4 • Do not let the tap run while you brush your teeth or soap your hands. • Check all leaky taps. • Take shorter showers. • Buy rechargeable batteries and a charger for them. • Avoid plastic bags. • Recycle your newspapers. COAL: During the carboniferous age, the earth had large amounts of plant life and dense forests in swampy and low-lying wetland areas. Plants and other life forms, after their death, drifted down to the bottom of the swamps, where they were compressed and decomposed to form peat. Coal was formed due to the compression of the peat at high temperature and pressure. As coal was formed from the remains of vegetation, it is also called a fossil fuel. Carbonisation is the slow process of conversion of dead vegetation into coal. Coal is the world’s most abundant fossil fuel. There was a time when it was used as a primary fuel for cooking and driving railway engines. It is now the largest source of fuel to generate electricity all over the world. Coal is primarily made up of carbon, hydrogen, oxygen, nitrogen and some amounts of
- 5. 5 sulphur. Coal is classified mainly into three types. They are anthracite, bituminous coal and lignite. Anthracite: Anthracite contains high carbon percentage around 92% - 98%. It is the highest carbon grade and used mainly to produce heat. Bituminous coal: It contains carbon percentage 60% -80% lesser than anthracite and used mainly for power generation. Lignite: It has low percentage of carbon 25%-35% and mainly used for power generation. Surface mining is used when coal is found close to the surface or hillsides. Underground mining is used to extract coal that is deep beneath the surface of the earth. Warren Hastings, the first governor general of West Bengal, initiated the commercial coal mining at Raniganj in the year 1774. Uses of coal: • It is a black in coloured solid used in railway engines as fuel in the olden days. • It is used in thermal power production. • Coal is the largest source of fuel used to generate electricity world-wide. • Coal is used in manufacturing industries for heat and power applications. • Coal is used to make steam for heating. • It is also used as coke in steel making. Coal is processed in the industry to get different products like coke, coal tar, coal gas, etc. Coke: • It is a porous and black colored substance. • It is a pure form of carbon. • It is used in the extraction of metals. And also used in the manfacture of steel. Coal tar: • It is a black thick liquid with an unpleasant smell. • It is a mixture of 200 substances. • The products obtained from coal tar are used as starting materials for manufacturing substances like dyes, drugs, explosives and perfumes. • Naphthalene balls, which are used to repel moths and other insects, are also obtained from coal tar. Bitumen, a petroleum product, is now used in place of coal tar for surfacing roads. Coal gas: Coal gas is obtained during the processing of coal to get coke. It is mainly used as a fuel in industries around coal processing plants.It is used more as a source of heat than light. In the year 1810, for the first time coal gas was used for street lighting in London. It is used as a fuel in many industries. PETROL :
- 6. 6 Petroleum, a natural resource formed from organisms living in the sea, is a dark and oily liquid mixture with a very unpleasant odour. The word petroleum comes from the Latin words ‘petro’ meaning rock and ‘leum’ meaning oil. Petroleum and natural gas are formed from compressed organic matter. As petroleum and natural gas are lighter than water, the deposits of petroleum and natural gas occur above that of water. The first oil well in the world was drilled in Pennsylvania, USA in the year 1859. After eight years, in the year 1867, oil was struck at Makum in Assam. Oil in India is found in Assam, Gujarat and Mumbai High, and in the river basins of Godavari and Krishna. Petroleum is a mixture of various constituents like petroleum gas, petrol, diesel, lubricating oil, paraffin wax, etc. The process of separating its many constituents is called refining. It is refined in a petroleum refinery. At the refinery, this crude oil mixture is separated or 'fractionated' into different components by fractional distillation. Light gases are the topmost fraction, followed by petrol and kerosene. Diesel is the heaviest. The other heavier fractions are not useful and are usually used to make asphalt to surface roads. Constituents of petroleum and their uses: • LPG or petroleum gas is used as a fuel for home and industry. • Petrol is used as a motor fuel, aviation fuel and a solvent for dry cleaning. • Kerosene is used as a fuel for stoves and lamps and also in jet aircraft. • Diesel is used as a fuel for heavy motor vehicles and electric generators.
- 7. 7 • Lubricating oil is used for many lubricating purposes. • Paraffin wax is used in ointments, candles and Vaseline. • Bitumen is used in paints and also to surface roads. • Petrochemicals are used in the manufacture of detergents, polyester and nylon fibres, polythene and other man-made plastics. Petroleum must be conserved as it is exhaustible fuel. Following graph indicates depletion in the availability of petroleum sources because of its over usage in the years. Thus it is important to conserve petroleum resource for future which can be done by following simple steps. Simple steps to reduce consumption of petrol/diesel: • Use public transport. • Combine many errands into one trip. • Car pooling to school and work. Burning petroleum releases carbon dioxide into the air, which contributes to global warming. Oil spills at sea are devastating to the animal and plant life in and around the sea. NATURAL GAS: Natural gas is another fossil fuel, like coal and petroleum. It is a non-renewable fuel. It is a very important component of the worl's energy supply.
- 8. 8 Natural gas is one of the most useful, clean and safe energy sources. It is a colourless and odourless gas. In its pure form and is made up of many gases of which methane is the most prominent. The chemical formula for methane is CH4. When natural gas burns, it gives off a great deal of energy. And unlike other fossil fuels it does not leaves any ash. It produces very little air pollution, as methane burns almost completely. It is one of the cleanest burning fuels and produces mostly heat, carbon dioxide and water vapour. Thus, it is said that it contributes to a cleaner and greener environment. Natural gas is odourless. To detect gas leaks, a harmless but pungent odorant that smells like rotten eggs is added to it, as a safety measure. It can be smelt in case of even a small leak. When natural gas is mixed with the correct amount of air and ignited, this colourless, invisible gas burns with a clean, blue flame. Natural gas is measured in British Thermal Units (BTU). About 2,500 years ago, the Chinese discovered that natural gas could be burned. They used bamboo to pipe it from shallow wells and burned it to boil seawater. This way they made water drinkable and separated the salt. Natural gas is compressed to a high pressure and stored in hard cylindrical or spherical containers, for distribution. It is then known as Compressed Natural Gas or CNG. CNG is also distributed to homes and industries through pipes. In India, such a network of pipelines exists in Vadodara in Gujarat and some parts of Delhi. CNG is now used as a fuel for transport vehicles – from light duty trucks, auto rickshaws and taxi cabs to delivery vans and heavy duty vehicles like buses. Uses: • Natural gas is useful for cooking foods. • It is also useful to run central heating and cooling systems and cloth dryers. • It is useful in the manufacture of fabrics, glass, steel, plastics, paint and other products. • It is the major sources of electricity generation through the use of gas turbines
- 9. 9 and steam turbines. Text Book Questions and Answers 1. Describe characteristics and uses of coke. (i)Coke is a tough,porous and black substance. (ii) It is almost pure form of carbon. Uses: Coke is used in the manufacture of steel and extraction of many metals. 2. Explain the process of formation of petroleum. Petroleum was formed from organisms living in the sea. As these organisms died, their bodies settled at the bottom of the sea and got covered with layers of sand and clay. Over millions of years in the absence of air, high temperature and high pressure the dead organisms transformed into petroleum and natural gas. 3. What are the advantages of using CNG and LPG as fuels? The advantages of using CNG and LPG are (i) CNG and LPG are clean fuels. (ii) Their cost is low. (iii) They can be used directly for burning. (iv) They do not produce pollution. (v) They can be easily transported; either in cylinders or through pipelines 4. Describe how coal is formed from dead vegetation. What is this process called? Millions of years ago, dense forests got buried under the soil due to natural processes like storms, floods, and earthquakes. These got compressed as more and more soil got deposited over them. When they got buried deep in the soil, they were exposed to very high pressure and temperature. Under these conditions, these slowly got converted into coal. This process of formation of coal from dead vegetation is called carbonization. 5. Explain why fossil fuels are exhaustible natural resources. (i)The formation of fossil fuels is a very slow process, which takes million of years in nature. (ii) Fossil fuels are present in limited quantity in the nature. (iii) They can be exhausted by human activities.
- 10. 10 (iv) So, fossil fuels are called exhaustible natural resources. 6. The following Table shows the total power shortage in India from 1991–1997. Show the data in the form of a graph. Plot shortage percentage for the years on the Y-axis and the year on the X-axis S.No. Year Shortage (%) 1 1991 7.9 2 1992 7.8 3 1993 8.3 4 1994 7.4 5 1995 7.1 6 1996 9.2 7 1997 11.5 Question Bank Very Short Answer Questions (1Mark) 1) Write any two examples of Inexhaustible Natural Resources? Sunlight, air 2) Write any two examples of exhaustible Natural Resources? Coal, petroleum 3) What is carbonization? The process of conversion of dead vegetation into coal is called carbonization. 4) When coal is heated in air, it burns and produces which gas? Carbon dioxide gas 5) What is coke?
- 11. 11 Coke is a tough, porous and black substance. It is almost pure form of carbon. 6) Write the uses of coke? Coke is used in the manufacture of steel and in the extraction of many metals. 7) What is coal tar? Coal tar is a black, thick liquid with unpleasant smell. 8) Name the petroleum product, is used in place of coal-tar for metalling the roads. Bitumen 9) How coal gas is produced? Coal gas is obtained during the processing of coal to get coke. 10) Name the fuels used to run light vehicles and heavy vehicles? Petrol, diesel 11) What are petrochemicals? Many useful substances are obtained from petroleum and natural gas. These are termed as ‘Petrochemicals’. 12) What is PCRA? Petroleum Conservation Research Association Short Answer Questions- Type -1 (2Mark) 1) Expand CNG and LPG? CNG: Compressed Natural Gas. LPG: Liquified Petroleum Gas 2. Coal is processed in industry to get some useful products? Name those products? Coal is processed in industry to get some useful products such as coke, coal tar and coal gas. 3. Products obtained from coal tar are used as starting materials for manufacturing various substances? Name that substances Synthetic dye, drugs, explosives, perfumes, plastics, paints, photographic materials, roofing materials etc. 4. What are the uses of coal gas? (i) Previously Coal gas was used for street lighting in London in 1810. (ii) Now a days, it is used as fuel in many industries. 5. Name the places where we find oil wells in India? In India, oil wells are found in Assam, Gujarat, Mumbai High and in the river basins of Godavari and Krishna. 6. What are the uses of petrochemicals? Petro chemicals are used in the manufacture of detergents, fibers polythene, fertilizers and other plastics. Short Answer Questions- Type -2 (3Mark) 1. What are the uses of coal? Coal is one of the fuels used to cook food. Earlier, it was used in railway engines to produce steam to run the engine. It is also used in thermal power plants to produce electricity.
- 12. 12 2. What is the difference between coal and coke? Coal Coke (a) It is a non-crystalline form of carbon. (a) It is an amorphous form of carbon. (b) It is obtained by the decay of (b) It is obtained by heating soft coal vegetation, in the which existed millions of years absence. or limited supply of air. ago. 3. Explain Refining of petroleum? Petroleum is a dark oily liquid. It has unpleasant odour. It is a mixture of various constituents such as petroleum gas, petrol, diesel, lubricating oil, paraffin wax, etc. The process of separating the various fractions of petroleum is known as refining. It is carried out in a petroleum refinery. 4. What are the tips given by Petroleum Conservation Research Association (PCRA) to people how to save petrol/diesel while driving? (i)Drive at a constant and moderate speed as far as possible. (ii) Switch off the engine at traffic lights or at a place where you have to wait, (iii)Ensure correct tyre pressure, (iv) Ensure regular maintenance of the vehicle. Long Answer Questions (5 Marks) 1. Name the Various constituents of petroleum and their uses S.No Constituents of petroleum Uses 1. Petroleum Gas in Liquid form(LPG) Fuel for home and industry 2. Petrol solvent for dry cleaning 3. Kerosene Fuel for stoves, lamps and for jet aircrafts 4. Diesel Fuel for heavy motor vehicles, electric generators 5. Lubricating oil Lubrication 6. Paraffin wax Ointments, candles, Vaseline etc. 7. Bitumen Paints, road surfacing 2. What is a fuel? What are the characteristic of a good fuel? A fuel is a form of matter, that is used to produce heat energy or power by its burning.The characteristics of a good fuel are: (a) It must be easily available.
- 13. 13 (b) It must have low cost. (c) It should be clean and odourless. (d) It should be easily transportable. (e) It should produce more energy, in proportion to its mass. (f) It should leave very little ash after burning. Activity Based Questions 1. Identify Exhaustible and Inexhaustible Natural Resources from the following. Coal LPG Sun Light Petroleum Air Ans. Exhaustible natural resources are: Coal, LPG and Petroleum. Inexhaustible natural resources are : Sunlight and Air. 2. Make the list of various materials used by us in daily life and classify them as natural and man-made. Ans.
- 14. 14 Multiple Choice Questions (1 Mark) 1) The following resources are present in unlimited quantity in nature and are not likely to be exhausted by human activities. a) Sunlight, air b) Petrol, coal c) Sun light, coal d) Coal, air 2) When coal is heated in air, it burns and produces a) Oxygen gas b) carbon dioxide gas c) Nitrogen gas d) all of these 3) The petroleum product, is used in place of coal-tar for metalling the roads a)Coke b)Coal gas c) Tar d)Bitumen 4) Coal gas was used for the first time in London in 1810 for a) Street lighting b) stove lighting c) Both a and b d) all of these 5) Heavy motor vehicles like trucks and tractors run on a) Petrol b) diesel c) kerosene d) coal 6) The world’s first oil well was drilled in a) Pennsylvania b) Washington c) New Zealand d) India 7) First oil well was drilled in India in the state a) Andhrapradesh b) Karnataka c) Assam d) Maharashtra 8) The other name for petroleum is a) Coal b) tar c) grease d) black gold 9) Burning of fossil fuels is a major cause of a) Water pollution b) air pollution c) volcano’s d) earthquakes 10) Coke is used in the manufacturing of a) Lead b) Iron c) steel d) Copper Natural Man-made Air Pen Water Book Sunlight Chair Soil Table Coal Vehicles Petrol Computer
- 15. 15 11) Which is an almost pure form of carbon? a) Coke b) Coal tar c) Coal gas d) None of these 12) Which gas is obtained during the processing of coal? a) Carbon dioxide b) Coal gas c) Carbon monoxide d) Sulphur dioxide 13) Petrol and diesel can be obtained from a) Coal tar b) Coal c) Petroleum d) Coal gas 14) Refining is a) Extracting petroleum gas b) Separation of various fractions of petroleum c) Heating of coal d) Sedimentation of fossil fuel 15) A natural gas stored under high pressure is called (a) CNG (b) LPG (c) KLG (d) PNP 16) Least polluting fuel for vehicle is (a) coke (b) kerosene (c) diesel (d) CNG 17) Main constituent of LPG is (a) methane (b) butane (c) ethane (d) propane Keys: 1) a 2) b 3) d 4) a 5) b 6) a 7) c 8) d 9) b 10) c 11) a 12) b 13) c 14) b 15) a 16) d 17) b Fill in the Blanks (1 Mark) 1) Exhaustible Natural Resources can be exhausted by ____________ 2) The process of conversion of dead vegetation into coal is called _____________ 3) Under high pressure and high temperature, dead plants get slowly converted to ________ 4) Coal tar is a mixture of about ________ substances. 5) Naphthalene balls used to repel __________. 6) __________ is used as a fuel in light automobiles such as motor cycles/ scooters and cars. 7) The first oil well in India was struck at _________ in Assam. 8) Fossil fuels are _____________, ______________and _________________. 9) Process of separation of different constituents from petroleum is called _____________. 10) Least polluting fuel for vehicle is ________________
- 16. 16 Keys: 1) Human activities 2) carbonization 3) coal 4) 200 5) moths and insects 6) Petrol 7) Makum 8) Coal, Petroleum and Natural gas 9) Refining 10) CNG (compressed natural gas) MATCH THE FOLLOWING A B 1) Sunlight ( ) a) Exhaustible 2) Natural gas ( ) b) manufacture of steel 3) Coke ( ) c) Inexhaustible 4) Coal tar ( ) d) unpleasant smell Keys: 1- c 2 - a 3 - b 4 – d MATCH THE FOLLOWING A B 1) Naphthalene balls ( ) a) metalling the roads. 2) Bitumen ( ) b) dark oily liquid True/False against the following statements: (a) Fossil fuels can be made in the laboratory. (T/ F) (b) CNG is more polluting fuel than petrol. (T/ F) (c) Coke is almost pure form of carbon. (T/ F) (d) Coal tar is a mixture of various substances. (T/ F) (e) Kerosene is not a fossil fuel. (T/ F) An s : (a) F (b) F (c) T (d) T (e) F 3) Petroleum ( ) c) power generation 4) Natural gas (CNG) ( ) d) repel moths Keys: 1 - d 2 - a 3 - b 4 - c