Doc Brown's GCSE/IGCSE KS4 science-CHEMISTRY Revision Notes

Oil, useful products, environmental problems, introduction to organic chemistry

1. Fossil Fuels - where do they come from?

What is a fossil fuel? What is the origin of coal, peat, oil, natural gas? What is the Carbon Cycle?

Index of KS4 Science GCSE/IGCSE Chemistry Oil & Organic Chemistry Pages: 1. Fossil Fuels : 2. Fractional distillation of crude oil & uses of fractions : 3. ALKANES - saturated hydrocarbons and combustion : 4. Pollution, carbon monoxide, nitrogen oxides, what makes a good fuel?, climate change-global warming : 5. Alkenes - unsaturated hydrocarbons : 6. Cracking - a problem of supply and demand, other products : 7. Polymers, plastics, uses and problems : 8. Introduction to Organic Chemistry - Why so many series of organic compounds? : 9. Alcohols - Ethanol - properties, reactions, biofuels : 10. Carboxylic acids and esters : 11. Addition polymers and condensation polymers : 12. Natural Molecules - carbohydrates - sugars - starch : 13. Amino acids, proteins, enzymes & chromatography : 14. Oils, fats, margarine and soaps : 15. Vitamins, drugs-analgesic medicines & food additives and aspects of cooking chemistry! : 16. Ozone, CFC's and free radicals : 17. Extra notes, ideas and links on Global Warming and Climate Change : Multiple Choice and Gap-Fill Quizzes: m/c QUIZ on Oil Products (GCSE/IGCSE easier-foundation-level) : m/c QUIZ on Oil Products (GCSE/IGCSE harder-higher-level) : IGCSE/GCSE m/c QUIZ on other Aspects of Organic Chemistry : and 3 Easy linked GCSE/IGCSE Oil Products word-fill worksheets

1. The origin of oil and other fossil fuels - what are they formed from?

• Crude oil is formed from organic material of the remains of plant and animal organisms that lived millions of years ago.  These remains form sediments e.g. at the bottom of seas, and  become buried under layers of sedimentary rock. They  decay, without air (oxygen), under the action of heat and pressure to form crude oil over millions of years.

  • Crude oil is a non-renewable energy resource taking millions of years to form from degraded organic biomass.

  • The vast majority of compounds found in crude oil are hydrocarbons, that is compounds/molecules made up of carbon atoms combined with hydrogen atoms.

• It is a fossil fuel because it is formed from once living organisms and the Sun is the original source of energy. It is a non-renewable and finite (limited reserves) energy resource because it takes millions of years to form and we burn it faster than its is formed! It is also known as a finite energy resource because it will eventually run out! We do not have unlimited oil reserves!

• Coal, peat and natural gas are the other principal non-renewable fossil fuels formed from the remains of plants or animals.

  • Coal, formed millions of years from the remains of tropical plant material, mainly consists of carbon,  Burning coal produces a lot of pollution as the greenhouse gas carbon dioxide. The pollutants include soot particles (black deposits of carbon), sulphur dioxide (lung irritant and acid rain gas) and poly-aromatic hydrocarbons which are carcinogenic.

    • The main reaction on burning is ...

    • carbon + oxygen ==> carbon dioxide

    • C_(s) + O_2(g) ==> CO_2(g)

  • Natural gas, mainly the hydrocarbon methane CH₄, is often found with oil. It consists of 25% by mass of hydrogen and 75% carbon, and, apart from the 'greenhouse' CO₂, produces far less pollution than coal on combustion.

    • The main reaction on burning is ...

    • methane + oxygen ===> water + carbon dioxide

    • CH_4(g) + 2O_2(g) ==> CO_2(g) + 2H₂O_(l)

  • Peat ('turf') is formed over hundreds-thousands of years from the decay of plant material in the absence of oxygen, in boggy-water logged ground. It is a poor quality fuel since the carbon content is much less than in coal and large amount of ash formed on combustion. However, there is a peat fired power station in Ireland.

• THE CARBON CYCLE: When the fossil fuels are burned the 'carbon', as carbon dioxide, is returned to the atmosphere of the Earth's environment. There, it gets absorbed by plant leaves and used up in photosynthesis with the help of sunlight energy and green chlorophyll. The plant material decays reforming carbon dioxide, or, is eaten by animals and used in respiration to form carbon dioxide. Either way, this completes the carbon cycle. See also evolution of Earth's atmosphere

  • photosynthesis: carbon dioxide + water ==> glucose + oxygen

    • 6CO₂ + 6H₂O ==> C₆H₁₂O₆ + 6O₂ 

  • respiration: glucose + oxygen ==> carbon dioxide + water

    • C₆H₁₂O₆ + 6O₂  ==> 6CO₂ + 6H₂O

    • and fossil fuel combustion, forest fires etc. all return carbon dioxide to the atmosphere

  •  Some of the carbon ends up as coal from decayed plants or oil from decayed animal remains i.e. fossil fuel formation, which ultimately also becomes part of the carbon cycle.

• POLLUTION PROBLEMS from burning fossil fuels are dealt with in section 4. Pollution, carbon monoxide, sulfur/nitrogen oxides, acid rain, a good fuel?, climate change

Multiple Choice Quizzes and Worksheets

KS4 Science GCSE/IGCSE m/c QUIZ on Oil Products (easier-foundation-level)

KS4 Science GCSE/IGCSE m/c QUIZ on Oil Products (harder-higher-level)

KS4 Science GCSE/IGCSE m/c QUIZ on other aspects of Organic Chemistry

and 3 linked easy Oil Products gap-fill quiz worksheets

ALSO gap-fill ('word-fill') exercises originally written for ...

... AQA GCSE Science Useful products from crude oil AND Oil, Hydrocarbons & Cracking etc.

... OCR 21st C GCSE Science Worksheet gap-fill C1.1c Air pollutants etc ...

... Edexcel 360 GCSE Science Crude Oil and its Fractional distillation etc ...

... each set are interlinked, so clicking on one of the above leads to a sequence of several quizzes

Advanced Level Organic Chemistry revision notes

Revise KS4 Science GCSE/IGCSE/O level Chemistry Revision-Information Study Notes for revising for AQA GCSE Science, Edexcel 360Science/IGCSE Chemistry & OCR 21stC Science, OCR Gateway Science WJEC/CBAC GCSE science-chemistry CCEA/CEA GCSE science-chemistry (and courses equal to US grades 8, 9, 10)

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