Alkanes: Saturated Hydrocarbon Compounds Used in Polymer Chains

1. 1) Alkanes are… • saturated hydrocarbon compounds • used to make polymer chains • toxic substances • unsaturated hydrocarbon compounds Answers a) saturated hydrocarbon compounds

2. 2) The chemical formula of propane is… • C4H8 • C2H6 • C3H8 • C3H6 Answers c) C3H8

3. 3)Which substance is used to distinguish between alkanes and alkenes? Answers bromine water

4. 4) Cracking involves the breaking down of… • alkenes into alkanes • large unsaturated hydrocarbon molecules into smaller, more useful, unsaturated hydrocarbons • large saturated hydrocarbon molecules into smaller, more useful alkanes, along with some alkenes • alcohols into alkenes Answers C) large saturated hydrocarbon molecules into smaller, more useful alkanes, along with some alkenes

5. 5) The chemical formula of ethene is… • C2H2 • C2H4 • C2H6 • C3H6 Answers b) C2H4

6. 6) Which one of the following compounds is unsaturated? • C4H8, b) C2H6, c) C3H8 d) C4H10 Answers. a) C4H8,

7. 7) Many ethene molecules combine together to make… • ethane • poly(propane) • poly(ethane) • poly(ethene) Answers d) poly(ethene)

8. 8) The polymer called poly(chloroethene) is also known as… • poly(ethane) • PVC • poly(propene) • PTFE Answers. b) PVC

9. 9) Small molecules that join together to make polymers are called… Answers. Monomers

10. 10) Which one of the following is not a sensible way of reducing the amount of polymers entering landfill sites? • recycling • incineration • reusing • fractional distillation Answers d) fractional distillation

11. 11) Describe how bromine is used to distinguish between alkenes and alkanes (3) Answers • Bromine water is brown. • When alkenes are added it turns colourless • When alkanes are added it remains brown

12. 12) What is the difference between unsaturated and saturated (2). Answers • Saturated contains no double bonds (alkanes) • Unsaturated contains atleast one double bond (alkenes).

13. 13) Name the first 4 alkanes (2) Answers Methane Ethane Propane Butane

14. 14) How many carbons does propane have? Answers 3

15. 15) What are the conditions for cracking? Answers Heat Catalyst

16. 16) What are some of the biggest problems with polymers? Answers • Non-biodegradable-don’t rot • They remain in landfill sites for many years

17. 17) What are biodegradable polymers? Answers. Made from starch molecules (natural) so when buried they are broken down by microorganisms.

18. 18) What are photodegradable polymers? Answers. Polymers that break down in sunlight.

19. 19) How are the products of crude oil separated. • Cracking • Fractional distillation • Thermal decomposition Answers b) Fractional distillation

20. 20) In fractional distillation of crude oil which one of these comes off at the top of the column a) Gases b) bitumen c) Petrol d) Kerosene Answers a) Gases

21. 21*) In fractional distillation of crude oil at the top of the column the following molecules come off. a) High boiling point, low viscosity, highly flammable hydrocarbon b) Low boiling point, low viscosity, highly flammable hydrocarbon c) High boiling point, low viscosity, low flammable hydrocarbon Answers b) Low boiling point, low viscosity, highly flammable hydrocarbon

22. 22) The larger the hydrocarbon.. • The higher the boiling point • The lower the boiling point Answers a) The higher the boiling point

23. 23) What are the products of the complete combustion of hydrocarbon? Answers Carbon dioxide + water

24. 24) When does incomplete combustion take place? Answers When there is a lack of oxygen-ie when gas heaters are not well ventilated.

25. 25) Why is incomplete combustion unsafe? Answers It produces a odourless gas called carbon monoxide which is poisonous.

26. 26) What are the four things that need to be considered when choosing the best fuel? Answers • Ease of ignition • Amount of energy released • Amount of smoke and ash produced. • How easy it is to store and transport.

27. 27) How is acid rain formed? Answers • Sulphur impurities in fossil fuels burn in oxygen to produce Sulphur dioxide. • Sulphur dioxide reacts with rain water to produce acid rain

28. 28) What are the problems with acid rain? (3) Answers • Lakes become acidic-plants and animals die • Kills trees • damages limestone buildings and statues.

29. 29) List three ways of reducing acid rain? (3) Answers • Line chimneys of power stations with alkali-neutralises acidic gases before released into the atmosphere. • Sulphur removed from fuels before they are burnt-low sulphur petrol. • Reduce use of fossil fuels.

30. 30) Give the name of the three main green house gases and explain how they cause the earth to heat-up (3) Answers. Carbon dioxide Methane Water vapour. They act like a blanket above the earth atmosphere to (trap) AND re-radiate back to earth

31. 31) Explain how iron seeding is used to reduce carbon dioxide levels (3). Answers. • Iron is needed by plants for photosynthesis. • Injecting iron into oceans promotes phytoplankton growth. • Phytoplankton absorb carbon dioxide from the atmosphere.

32. 32*) Explain how carbon capture is used to reduce carbon dioxide levels (3). Answers. • This involves converting waste CO2 to useful hydrocarbons. • Short chain hydrocarbon are easy to make but longer chains (needed for petrol) are more difficult to produce) (Require, high temperature and pressure and a catalyst)

33. 33*) What is biogas ? Answers. Produced by microorganism which decompose living organism waste/dead plants which is used as fuel.

34. 34*) What is bioethanol ? Answers. • Sugar cane and sugar beet can be used as sources of sugar. • The sugars are then fermented by using yeast to produce ethanol which is used as fuel.

35. 35) Name four advantages of using biofuel? Answers. • They are clean fuel and does not produce carbon particulates • They are renewable • They are carbon neutral and add less carbon dioxide to the atmosphere compared to fossil fuels. • Less crude oil is used as fuel and so the reserves will last longer.

36. 36) Name four disadvantages of using biofuel? Answers. • Land is needed to grow biofuels and so there is less land available for growing food and for homes. • This may lead to a shortage of food and food prices rising • Lots of crops required to provide a small amount of bio-methane • When making biofuels energy is needed to transport the crops and to fertilise the crops. • Bad season reduces availability of biofuels.

37. 37) Which gases do fuel cells combine to produce energy? Answers. Hydrogen and Oxygen

38. 38) List 5 advantages of fuel cells? Answers. • They are much more efficient than batteries or power station • Electricity is directly produced from the reactions so no turbines are needed. • Don’t produce CO2-so don’t contribute global warming • Don’t release SO2-don’t contribute to acid rain. • Only by-product is water-which is harmless.

39. 39)What are the major disadvantages of fuel cells? Answers. • A lot of energy is needed to make Hydrogen from water in the first place. This means burning fossil fuels is required, but to a smaller extent. • Hydrogen is both highly explosive and flammable, so transport and storage can be a problem.