nss chemistry part 5 & 11 chemistry of carbon compounds

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HKCEE & HKAL Past Paper Questions: Part 5 Fossil Fuels and Carbon Compounds Part 11 Chemistry of Carbon Compounds Section A: Multiple Choice Questions Fossil Fuels 1. HKCEE 1995 Q42

Which of the following products may be formed from the cracking of heavy oil fraction? (1) CO (2) C2H4 (3) C8H18 A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

Ans: C HKCEE 1997 Q23-24 Directions : Q.2 and Q.3 refer to the following experiment :

2. Which of the following set-ups should be connected to the delivery tube to collect the gaseous products

formed? A. C.

B. D.

Ans: D

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3. Which of the following reactions is involved in this experiment? A. cracking B. redox C. catalytic hydration D. destructive distillation

Ans: A 4. HKCEE 2002 Q9

Which of the following equations represents a cracking reaction? A. C4H8 + H2 C4H10 B. C4H10 C3H6 + CH4 C. C6H12O6 2C2H5OH + 2CO2 D. C4H9OH C4H8 + H2O

Ans: B 5. HKCEE 2005 Q2

Upon cracking, one molecule of decane (C10H22) gives two molecules of propene and one molecule of an alkane (X). What is X?

A. C4H6 B. C4H10 C. C7H14 D. C7H16

Ans: B 6. HKCEE 2008 Q14 Which of the following petroleum fractions has the highest carbon content? A. diesel B. petrol C. kerosene D. naphtha

Ans: A 7. HKCEE 2010 Q2 Consider the industrial processes as shown below :

Which of the following combinations is correct ? Process I Process II

A. is a chemical change. is a physical change. B. is a chemical change. is a chemical change. C. is a physical change. is a physical change. D. is a physical change. is a chemical change.

Ans: D

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Pollutions 8. HKCEE 1997 Q38

Which of the following statements about using ethanol as a car fuel is correct? (1) Ethanol is a cleaner fuel than petrol. (2) Using ethanol as a car fuel is economical in agricultural countries with sugar canes the main crop. (3) A car engine has to be suitably modified when using ethanol as a fuel. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

Ans: D

9. HKCEE 1998 Q7 Which of the following environmental problems is NOT caused by excessive burning of fossil fuels?

A. the corrosion of marble status B. the formation of smog C. a higher incidence of liver diseases D. global warming

Ans: C 10. HKCEE 1999 Q30 Which of the following combinations is INCORRECT? Pollutant Harmful effect A. hydrocarbons causing liver diseases B. carbon monoxide causing unconsciousness C. lead compounds causing brain damage D. carbon particles causing respiratory diseases


Which of the following pairs is correctly matched? Pollutant Effect A. carbon monoxide global warming B. sulphur dioxide darkening of building walls C. lead compounds liver disease D. unburnt hydrocarbons lung cancer

Ans: D

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12. HKCEE 2007 Q26 Which of the following statements concerning the measures to reduce air pollutants is/are correct?

(1) Scrubber can be used to reduce carbon monoxide. (2) Catalytic converter can be used to reduce nitrogen monoxide. (3) Electrostatic precipitator can be used to reduce unburnt hydrocarbons. A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only

Ans: B 13. HKCEE 2009 Q16 Which of the following is / are renewable energy source(s)?

(1) natural gas (2) wind power (3) nuclear energy A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only

Ans: B 14. HKCEE 2009 Q26 Which of the following measures can help reduce the level of carbon monoxide at the road side?

(1) using liquefied petroleum gas as fuel for motor vehicles (2) installing catalyic converter for motor vehicles (3) installing electrostatic precipitator for motor vehicles A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

Ans: A 15. HKCEE 2010 Q27 Which of the following environmental problems may be reduced by installing catalytic converters in

petrol-driven cars ? (1) acid rain (2) greenhouse effect (3) photochemical smog A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

Ans: B

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16. HKCEE 2010 Q25 Which of the following measures can help improve the air quality in Hong Kong ?

(1) Use natural gas to replace coal in generating electricity. (2) Use electricity to replace petrol to drive cars. (3) Use fuel with lower sulphur content to drive ferries. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

Ans: D Homologous series 17. HKCEE 1995 Q29

Which of the following compounds have the same empirical formula? (1) ethene (2) ethane (3) propene (4) propane A. (1) and (2) only B. (1) and (3) only C. (2) and (4) only D. (3) and (4) only


Which of the following are characteristics of a homologous series? (1) Members of the series can be represented by the same general formula. (2) Members of the series have same physical properties. (3) Members of the series have similar chemical properties. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)


Which of the following compounds represents the first member of a homologous series? A. ethane B. ethene C. ethanol D. ethanoic acid

Ans: B

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20. HKCEE 1998 Q17 Which of the following statements concerning the compounds C2H4, C3H6 and C4H10 is correct? A. They belong to the same homologous series. B. They are unsaturated hydrocarbons. C. They are gases at room temperature and pressure. D. They have the same physical properties.

Ans: C 21. HKCEE 2000 Q8

Which of the following statements concerning members of a homologous series is INCORRECT? A. They contain carbon and hydrogen only. B. They can be represented by the same general formula. C. They have similar chemical properties. D. Their boiling points increase with their relative molecular masses.

Ans: A 22. HKCEE 2001 Q32 The formulae of three straight-chain hydrocarbons are listed below:

(1) C2H6 (2) C3H6 (3) C4H8

Which of these hydrocarbons is/are unsaturated? A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only

Ans: D 23. HKCEE 2003 Q8 Which of the following combinations is correct? Homologous series General formula A. alkanes CnH2n B. alkenes CnH2n+2 C. alkanols CnH2nOH D. alkanoic acids CnH2n+1CO2H

Ans: D 24. HKCEE 2007 Q4 Which of the following statements concerning members of a homologous series is correct?

A. The members have the same molecular formula. B. The relative molecular mass of each successive member differs by 14. C. The volatility of the members increases with relative molecular mass. D. The members with more carbon atoms in their molecules burn more readily.

Ans: B

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Naming of Organic Compounds 25. HKCEE 1995 Q15

The structural formula of a certain compound is shown below.

The name of this compound is A. butan-1-ol. B. butan-2-ol. C. 2-methylpropan-1-ol. D. 2-methylpropan-2-ol.

Ans: C 26. HKCEE 2003 Q17 An organic compound has the following structure:

The systematic name of this compound is

A. 1,2-dimethyethanol. B. 1-methylpropan-1-ol. C. 1-methylpropan-2-ol. D. butan-2-ol.

Ans: D 27. HKCEE 2005 Q1

What is the systematic name of the following hydrocarbon?

A. 1,1,2-trimethylpropane B. 2,3,3-trimethylpropane C. 1,2-dimethylbutane D. 2,3-dimethylbutane

Ans: D

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28. HKCEE 2007 Q8 What is the systematic name of the following compound?

A. 2-chloro-2-ethylpropane B. 2-chloro-2-methylbutane C. 1-chloro-1,1-dimethylpropane D. 2-chloro-2,2-dimethylpropane

Ans: B 29. HKCEE 2008 Q6 An organic compound has the following structure :

The systematic name of this compound is A. 2-ethylpropan-2-ol. B. 2-methylbutan-1-ol. C. 2-methylbutan-2-ol. D. 1,1-dimethylpropan-1-ol.

Ans: C 30. HKCEE 2009 Q11 What is the systematic name of the following compound?

A. 2-bromobut-3-ene B. 3 -bromobut-1-ene C. 1 -bromo-1-methylpropene D. 3 -bromo-3-methylpropene

Ans: B

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31. HKCEE 2010 Q12 The structure of compound R is shown below :

The systematic name of R is

A. 2-methylbutan-3-ol. B. 3-methylbutan-2-ol. C. 1,1-dimethylpropan-2-ol. D. 3,3-dimethylpropan-2-ol.

Ans: B Alkanes 32. HKCEE 2003 Q33 Ethane reacts with bromine under suitable conditions. Which of the following statements concerning this

reaction is/are correct? The reaction occurs readily in the dark. The reaction is a substitution. The reaction gives a mixture of organic products. (1) only (2) only (1) and (3) only (2) and (3) only

Ans: D 33. HKCEE 2004 Q42 The structure of two organic compounds are shown below:

Which of the following statements concerning the two compounds are correct? (1) Both compounds are members of the same homologous series. (2) Both compounds have the same molar volume at room temperature and pressure. (3) Both compounds undergo substitution when treated with bromine. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

Ans: D

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34. HKCEE 2008 Q24 When chlorine reacts with methane under sunlight, which of the following compounds can be formed? (1) chloromethane (2) dichloromethane (3) hydrogen chloride A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

Ans: D 35. HKCEE 2010 Q14 What mass of methane upon complete combustion gives 0.90 g of water ?

(Relative atomic masses: H= 1.0, C= 12.0, O = 16.0) A. 0.40 g B. 0.45 g C. 0.75 g D. 0.80 g

Ans: A Alkenes 36. HKCEE 2002 Q44 Both ethene and ethyne are gaseous hydrocarbons. Their structures are shown below:

Which of the following statements concerning ethene and ethyne are correct? (1) Both are unsaturated hydrocarbons. (2) Both are insoluble in water. (3) Ethyne burns with a more sooty flame than ethene. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

Ans: D

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37. HKCEE 2003 Q31 Propene is an unsaturated hydrocarbon. Which of the following reactions is/are characteristic of the unsaturated

nature of propene? (1) It undergoes incomplete combustion to give carbon monoxide. (2) It decolourises acidified potassium permanganate solution. (3) It undergoes polymerization to give polypropene. A. (1) only B. (2) only C. (1) and (3) only D.(2) and (3) only


What is the type of reaction involved when hydrogen bromide reacts with ethene to form bromoethane? A. addition B. cracking C. polymerisation D. substitution

Ans: A 39. HKCEE 2006 Q16 Which of the following compounds is formed from the reaction of propene with chlorine?

Ans: B

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40. HKCEE 2007 Q27 Which of the following statements concerning but-2-ene are correct?

(1) It has the same molecular formula as but-1-ene.

(2) It can form a polymer with as the repeating unit.

(3) It can decolourise acidified potassium permanganate solution.

A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

Ans: D 41. HKCEE 2008 Q13 Which of the following statements concerning the reaction between acidified potassium permanganate solution

and excess propene is INCORRECT? A. The oxidation number of manganese changes from +7 to +2. B. The reaction occurred is an addition reaction. C. The acidified potassium permanganate solution is decolourized. D. The structure of the organic product is OH.CH(OH)CHCH 222

Ans: D 42. HKCEE 2009 Q24 Which of the following substances can react with acidified potassium permanganate solution?

(1) propene (2) potassium iodide solution (3) sodium sulphite solution A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)


Which of the following statements concerning alkenes is INCORRECT? A. They can decolorize a solution of bromine in 1,1,1-trichloroethane. B. They can decolorize red litmus solution. C. They can decolorize acidified potassium permanganate solution. D. They can be polymerized to form addition polymers.

Ans: B

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44. HKCEE 1997 Q18 The model shown below represents a compound containing 6 hydrogen atoms (white spheres) and 3 carbon

atoms (black spheres).

Which of the following statements concerning the compound is INCORRECT? A. Its structural formula is C3H6. B. It can be prepared by cracking petroleum fractions. C. It can decolorize bromine in 1,1,1-trichloroethane.

D. It can undergo polymerization.

Ans: A 45. HKCEE 1999 Q44 Which of the following statements concerning the reaction of an alkane with bromine are correct?

(1) The reaction occurs faster under sunlight than in darkness. (2) The reaction is a substitution reaction. (3) The colour of the reaction mixture fades. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

Ans: D

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Alkanols HKCEE 1996 Q23-24 Directions : Q.46 and Q. 47 refer to the following experiment. 46. A reaction mixture containing acidified potassium dichromate solution and ethanol is heated using the set-up

shown below :

In this experiment, the reaction mixture is undergoing A. reflux. B. distillation. C. emulsification. D. fractional distillation.

Ans: A 47. Which of the following statement concerning this experiment is correct?

A. The acidified potassium dichromate solution acts as a catalyst. B. The reaction mixture gradually becomes brown. C. Ethanol is reduced during the experiment. D. Ethanoic acid is formed during the experiment


Which of the following statements concerning propan-1-ol are correct? (1) Propan-1-ol can be used as a solvent. (2) Propan-1-ol can undergo polymerization. (3) Propan-1-ol can undergo esterification with ethanoic acid in the presence of concentrated sulphuric acid. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only

D. (1), (2) and (3)

Ans: B

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49. HKCEE 1997 Q20 When a glass of wine is left overnight, it becomes sour. Which of the following reactions is responsible for this

change? A. fermentation B. oxidation C. dehydration D. esterification

Ans: B

50. HKCEE 1997 Q22 Which of the following statements concerning the compound, CH3COOCH2CH3, is correct?

A. It is a food preservative. B. It has a pleasant smell. C. Its systematic name is methyl ethanoate. D. It is an electrolyte.

Ans: B HKCEE 1999 Q26-27 Directions : Q.51and Q.52 refer to the following experiment: 51. Some concentrated sulphuric acid and pumice stones were added to an alkanol and an alkanoic acid. The

mixture was heated under reflux for some time and the following compound was obtained;

Which of the following combination is correct? Alkanol Alkanoic acid A. methanol ethanoic acid B. methanol propanoic acid C. ethanol ethanoic acid D. ethanol propanoic acid

Ans: B

52. Which of the following statements concerning the experiment is correct? A. Concentrated sulphuric acid acts as an oxidizing agent in the reaction. B. The purpose of using pumice stones is to speed up the reaction. C. A fractionating column should be used in the experimental set-up. D. Heating under reflux can prevent the loss of reactants and products.

Ans: D

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53. HKCEE 2001 Q21 Which of the following statements concerning ethanol and butan-2-ol is INCORRECT? A. Both compounds can dissolve iodine. B. Both compounds can be represented by the same general formula. C. The boiling point of ethanol is higher than that of butan-2-ol. D. Each compound can be obtained by catalytic hydration of the corresponding alkene.

Ans: C HKCEE 2004 Q27-28 Directions : Questions 54 and 55 refer to the following information. 54. Ethene can be prepared by heating ethanol with excess concentrated sulphuric acid. The reaction involved can

be represented by the equation:

CH3CH2OH CH2=CH2 + H2Oconc. H2SO4

The type of reaction involved in the preparation is

A. cracking. B. condensation. C. addition. D. dehydration.

Ans: D 55. Which of the set-ups shown below can be used to collect the ethane produced? (Relative atomic masses : H = 1.0, C = 12.0, N = 14.0, O = 16.0) (1)

(2) (3)


Ans: B

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56. HKCEE 2007 Q23

Which of the following statements concerning is/are correct?

(1) It is neutral to litmus (2) Its systematic name is propanol.

(3) When it reacts with ethanoic acid, the ester formed is .

A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only

Ans: C 57. HKCEE 2009 Q25 Which of the following hazard warning labels should be displayed on the reagent bottle of methanol?

A. (1) and (2) only B. (l) and (3) only C. (2) and (3) only D. (l), (2) and (3)

Ans: A 58. HKCEE 2010 Q7 In an experiment, a mixture of ethanol and acidified potassium dichromate solution is heated under reflux to

obtain ethanoic acid. Which of the following apparatus should be used in the experiment ? A. stopper B. thermometer C. fractionating column D. water condenser

Ans: D

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59. HKCEE 2009 Q13 A drunken driver breathes into a device containing dichromate ions. The oxidation number of chromium would

change from A. +6 to +3. B. +3 to +6. C. +3 to +2. D. +2 to +3.

Ans: A Alkanoic acids & Esters 60. HKCEE 2001 Q25 The reaction involved in the preparation of ethanoic acid from ethanol is

A. an addition. B. a condensation. C. a redox. D. a dehydration.

Ans: C 61. HKCEE 2003 Q38 The structures of two organic compounds are shown below:

Which of the following statements concerning these two compounds is/are correct? (2) They have the same relative molecular mass. (3) They have the same chemical properties. (4) They are both soluble in water. A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only

Ans: A

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62. HKCEE 2004 Q17 The following paragraph was extracted from the laboratory report of a student on the preparation of an organic

compound.

CH3CH2CO2H and CH3CH2OH were heated with a small amount of concentrated H2SO4 in a test tube for a few minutes. The resultant mixture was then added to a beaker of cold water.

Which of the following statements concerning the experiment is correct?

A. The compound prepared was ethyl ethanoate. B. Concentrated H2SO4 acted as an oxidizing agent. C. The preparation involved a condensation. D. When the resultant mixture was added to the cold water, a white precipitate was formed.


Which of the following molecular formulae represents an alkanoic acid? A. CH2O B. CH2O2 C. C2H2O2 D. C2H6O2

Ans: B 64. HKCEE 2007 Q16 A mixture containing 25 cm3 of CH3CH2CH2OH, 25 cm3 of CH3COOH and 1 cm3 of concentrated H2SO4 is

heated under reflux. After some time, a pleasant smell is detected. Which of the following statements concerning this experiment is correct?

A. A redox reaction is involved. B. The reaction cannot go to completion. C. Concentrated H2SO4 acts as a reactant. D. One of the products is ethyl propanoate.

Ans: B

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65. HKCEE 2008 Q47 The empirical formula of an organic compound T is OCH2 . Effervescence occurs when T is added to sodium

carbonate solution. T may be (1) 3HCOOCH . (2) CH(OH)COOHCH3 . (3) COOHCHCHCH 223


Ans: B 66. HKCEE 2009 Q27 Esters can be used to make

(1) perfumes. (2) food additives. (3) solvent for paints. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

Ans: D

67. HKCEE 2010 Q18 The structures of compounds P and Q are shown below:

Which of the following statements is correct ?

A. P and Q are both acids. B. P is more volatile than Q. C. P dissolves in water readily but Q does not. D. P and Q both decolourise bromine water rapidly.

Ans: C

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Polymers 68. HKCEE 1995 Q22 The formula below can be used to represent the structure of some polymers.

(X represents an atom or a group of atoms.)

Which of the following combination is INCORRECT? X Name of polymer A. H polyethene B. Cl polyvinyl chloride C. CH3 perspex D. C6H5 polystyrene

Ans: C

69. HKCEE 1995 Q41 Which of the following statements concerning the recycling of plastics are correct?

(1) The recycling of plastics can help to solve the disposal problem of plastics. (2) The recycling of plastics can save raw materials derived from petroleum. (3) It is difficult to separate different types of plastics in the recycling process. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

Ans: D 70. HKCEE 1997 Q40 Which of the following methods can be used to solve the pollution problems associated with the disposal of

plastic waste? (1) recycling of plastics (2) making biodegradable plastics (3) burning plastic waste in incinerators with tall chimneys A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

Ans: A

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71. HKCEE 2000 Q15 A polymer has the following structure:

What is the monomer of this polymer? A. butane B. but-1-ene C. but-2-ene D. 2-methylpropene


Some concentrated sulphuric acid was poured into a sink connected to a catchpot made of polyvinyl chloride

(PVC). After some time, the catchpot became deformed. Which of the following explanations for the deformation of the catchpot is/are correct? (1) The heat liberated when the concentrated sulphuric acid mixed with the water in the catchpot caused PVC

to soften. (2) PVC was decomposed into its monomers by the concentrated sulphuric acid. (3) PVC was oxidized by the concentrated sulphuric acid. A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only

Ans: A

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73. HKCEE 2001 Q9 Which of the following statements concerning uses of plastics is correct? Perspex is used for making ash trays. Polyvinyl chloride is used for making raincoats. Polystyrene is used for making floor tiles. Nylon is used for making packaging materials for electrical appliances.


Which of the following compounds is a monomer of polyvinyl chloride (polychloroethene)? A. CH2 = CHCl B. CH2 = CCl2 C. CHCl = CHCl D. CCl2 = CCl2

Ans: A 75. HKCEE 2003 Q36 Which of the following statements concerning thermoplastics is/are correct?

(1) They soften upon heating (2) They are cross-linked polymers. (3) They are addition polymers. A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only

Ans: A 76. HKCEE 2004 Q15 The structure of polymer X can be represented by

CH3

CH3

CC

H

H

C

H

H CH3

CH3

C C

H

H CH3

CH3

C

What is the monomer of X?

A. 1,1-dimethylethene B. 1,2-dimethylethene C. methylpropene D. but-1-ene

Ans: C

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77. HKCEE 2004 Q41 Which of the following statements concerning polyvinyl chloride (PVC) are correct? (1) PVC is used in making raincoats. (2) PVC softens upon gentle heating. (3) When PVC is strongly heated, fumes with an irritating odour are emitted. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

Ans: D 78. HKCEE 2007 Q9 Which of the following items can be made from polystyrene? A. clothing B. food wrap C. electric socket D. packaging material

Ans: D

79. HKCEE 2010 Q10 The polymer formed from the polymerisation of 1,1-dichloroethene is commonly used in making food wrap for

microwave cooking. Which of the following can represent a part of the structure of the polymer ?

Ans: D

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Detergents 80. HKCEE 1996 Q18

When a little detergent is added to a drop of water on a piece of woollen cloth as shown above, the drop spreads. Which of the following statements correctly explains this observation? A. The detergent dissolves readily in water. B. The detergent has a polar end which is hydrophilic. C. The detergent can form an emulsion with water. D. The detergent can reduce the surface tension of water.

Ans: D HKCEE 1996 Q28-29 Direction : Q.81 and Q.82 refer to the following experiment used to study the causes of hardness of water.

81. A student added some soap solution to four test tubes containing the same volume of different aqueous solutions of the same molarity. He shook the tubes and measured the minimum volume of soap solution needed to form a permanent lather. The results are tabulated below:

Aqueous solution Minimum volume of soap solution needed to form a permanent lather / cm3

Sodium chloride 0.6

Calcium chloride 9.3

Potassium chloride 0.9

Magnesium chloride 8.5

Which of the following apparatus would be most suitable for measuring the volume of soap solution?

A. 50 cm3 burette B. 50 cm3 measuring cylinder C. 25 cm3 pipette D. 10 cm3 beaker

Ans: A

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82. Which of the following substances is/are responsible for the hardness of water? (1) sodium chloride (2) calcium chloride (3) potassium chloride (4) magnesium chloride A. (1) only B. (2) only C. (1) and (3) only D. (2) and (4) only

Ans: D 83. HKCEE 1998 Q15 A detergent has the following structure :

Which of the following statements concerning the detergent is correct? A. Its hydrocarbon chain is hydrophilic. B. It can be manufactured from vegetable oil. C. It is readily degraded by micro-organisms. D. It acts as an emulsifier in the cleaning process.


Which of the following problems are associated with excessive use of soapless detergents? (1) They can cause skin allergies. (2) They form foam when discharged into rivers and lakes. (3) They form scum when discharged into the sea. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

Ans: A

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85. HKCEE 1999 Q43 Which of the following statements concerning a soapless detergent are correct? (1) It can be prepared by heating a cooking oil with sodium hydroxide solution. (2) It acts as a wetting agent by reducing the surface tension of water. (3) It acts as an emulsifying agent in the cleaning process. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)


Which of the following statements concerning soaps are correct? (1) They are esters. (2) They can reduce the surface tension of water. (3) Their aqueous solutions are alkaline. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

Ans: C

87. HKCEE 2001 Q16 Which of the following statements is correct for a soapy detergent but incorrect for a soapless detergent? A. Its structure consists of a hydrophilic part and a hydrophobic part. B. It forms lather when shaken with distilled water. C. It can be made by reacting a vegetable oil with an alkali. D. It acts as an emulsifier in the cleaning process.

Ans: C 88. HKCEE 2002 Q21 In a boiler using hard water, scale is deposited on its interior after a period of time. The scale consists mainly of

metal carbonates. Which of the following substances can be used to remove the boiler scale? A. soapless detergent B. chlorine bleach C. sodium hydroxide solution D. vinegar

Ans: D

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89. HKCEE 2002 Q35 A student heated a mixture of fat and sodium hydroxide solution for some time. He then added the mixture to a

beaker of saturated sodium chloride solution. A white solid was formed. Which of the following statements concerning this experiment is/are correct? (1) The reaction between fat and sodium hydroxide is esterification. (2) The white solid is a soap. (3) The white solid contains salts of alkanoic acids. A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only

Ans: D 90. HKCEE 2003 Q19 Soap was prepared by heating fat with sodium hydroxide solution for some time. Concentrated sodium chloride

solution was then added to the resulting mixture. The purpose of adding concentrated sodium chloride solution is A. to help the precipitation of the soap. B. To enhance the cleansing power of the soap. C. To reduce the alkalinity of the soap. D. To act as a preservative for the soap.

Ans: A 91. HKCEE 2003 Q29 A detergent has the structure shown below:

Which of the following statements concerning this detergent is correct? A. It is non-biodegradable. B. It functions well in hard water. C. It can be manufactured from vegetable oils. D. The portion, CH3(CH2)10CH2–, is hydrophilic.


Which of the following substances is NOT used for the preparation of soaps?

A. vegetable oil B. sodium hydroxide solution C. concentrated sodium chloride solution D. concentrated sulphuric acid

Ans: D

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93. HKCEE 2005 Q42 Which of the following statements concerning soaps are correct?

(1) Soaps are biodegradable. (2) Soaps have good cleaning power in hard water. (3) The structure of a soap particle consists of a hydrophilic part and a hydrophobic part.



Which of the following statements concerning the cleansing action of a detergent are correct?

(1) It reduces the surface tension of water. (2) It acts as an emulsifying agent. (3) It reacts with grease to form soluble products.



Which of the following materials is/are used in the production of soap? (1) petroleum fractions (2) sodium hydroxide (3) sulphuric acid


Ans: B 96. HKCEE 2008 Q35 Which of the following statements concerning a soapy detergent is correct? A. It can increase the surface tension of water. B. It contains a hydrophobic hydrocarbon chain. C. It can be manufactured from petroleum products. D. It contains a positive ionic part for carrying out emulsification.

Ans: B

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97. HKCEE 2010 Q41 The structure of a detergent is shown below :

CH3(CH2)15COO－Na+

Which of the following statements concerning this detergent is correct ? A. It is non-biodegradable. B. It forms scum in sea water. C. It is manufactured from petroleum. D. The hydrophilic part responsible for its cleansing action is Na+

Ans: B Miscellaneous 98. HKCEE 1996 Q14 One mole of each of the following compounds is burnt completely in oxygen. Which compound requires the

greatest volume of oxygen, measured at the same temperature and pressure, for complete combustion? A. carbon monoxide B. ethane C. ethene D. ethanol

Ans: B 99. HKCEE 1998 Q29 X is a compound containing four carbon atoms. It gives negative results with the following tests.

Test

(1) Treating X with sodium hydrogencarbonate solution

(2) Treating X with a solution of bromine in 1,1,1-trichloroethane

(3) Heating X with acidified potassium dichromate solution

The structure formula of X may be A. CH3CH2CH=CH2. B. CH3CH2CH2CH2OH. C. CH3CH2CH2CO2H. D. CH3CO2CH2CH3.


Which of the following substances has the lowest boiling point? A. ethanol B. propan-1-ol C. propane D. butane

Ans: C

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101. HKCEE 2000 Q24 Which of the following compounds is insoluble in water? A. methanol B. methanoic acid C. methyl methanoate D. sodium methanoate

Ans: C 102. HKCEE 2006 Q12

Consider the following information:

Compound Relative molecular mass

CH3CH2OH 46

CH3CH2OCH3 60

CH3CH2CO2CH3 88

C6H12O6 180

When 1 g of each of these compounds undergoes complete combustion, which one will produce the greatest number of moles of carbon dioxide?

A. CH3CH2OH B. CH3CH2OCH3 C. CH3CH2CO2CH3 D. C6H12O6

Ans: B 103. HKCEE 2010 Q38 Compound E rapidly decolourises cold acidified potassium permanganate solution. When E is added to sodium

hydrogencarbonate solution, effervescence occurs. Which of the following compounds may E be?

Ans: A 104. HKCEE 2008 Q36 Which of the following processes does NOT involves redox reaction(s)? A. bromination of methane B. electrolysis of sea water C. thermal decomposition of limestone D. removal of air pollutants in car exhaust by catalytic converter.

Ans: C

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105. HKCEE 2009 Q12 An organic compound X has the molecular formula C3H4F2. Which of the following statements

concerning X is correct ? A. X has at least four possible structures. B. X must be a saturated compound. C. X turns acidified potassium dichromate solution from orange to green. D. X can be used to make a thermosetting plastic by addition polymerisation.

Ans: A

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Section B: Structural Questions Fossil Fuels 1. HKCEE 1996 Q3 ‘Fossil fuels’ such as petroleum and coal constitute the world’s major source of energy. However, many

countries have been developing alternative energy sources. (a) Why are petroleum and coal called ‘fossil fuels’?

(b) Give TWO reasons why it is necessary to develop alternative energy sources. (c) Nuclear power is used as an alternative to fossil fuels in many countries. Suggest ONE advantage and

ONE disadvantage of using nuclear power. (d) Suggest ONE energy source, other than nuclear power, that can be used as an alternative to fossil fuels.

(6 marks)

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2. HKCEE 1997 Q9 The photograph below shows a gas burner with a can of fuel. The can contains 250g of liquid butane.

(i) Write the structural formula of butane. (ii) (1) Write the chemical equation for the complete combustion of butane.

(2) Suggest a chemical test for EACH of the products formed when butane is completely burnt in air. (3) Calculate the volume of the gaseous product formed, measured at room temperature and pressure, if all the butane contained in the can is completely burnt in air.

(iii) Explain why it is dangerous to use such gas burners in a poor-ventilated room. (Relative atomic masses: H = 1.0, C = 12.0, O = 16.0; molar volume of gas at room temperature and pressure = 24.0 dm3)

(9 marks)

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3. HKCEE 2000 Q8a (a) Crude oil is a mixture consisting mainly of alkanes. Fractional distillation of crude oil gives different

petroleum fractions. The table below lists the length of carbon chain of the alkanes in some of the fractions.

Fraction Length of carbon chain

petrol/naphtha C5 – C10

kerosene C11 – C18

diesel C18 – C25

X C20 – C34

(i) Describe the principle underlying the fractional distillation of crude oil. (ii) (1) Explain why the global demand for petrol is greater than that for kerosene.

(2) Cracking kerosene can produce petrol. State the conditions required for the cracking process.

(iii) In Hong Kong, naphtha instead of coal is used to manufacture town gas. (1) State ONE advantage of using naphtha instead of coal to manufacture town gas. (You are NOT

required to consider the price of the materials.) (2) Explain why an additive with a foul smell is added to town gas before it is delivered to

consumers. (iv) Give ONE use of fraction X in cars.

(9 marks)

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4. HKCEE 2001 Q1 The photograph below shows a burning candle:

(a) The candle was is a petroleum product. What type of compounds is mainly present in the wax? (b) (i) In which of the following states does wax act as the fuel in a burning candle?

solid, liquid, vapour (ii) State the conditions required for the combustion of wax. (iii) Suggest a reason why a burning candle can be extinguished by a strong wind.

(c) Explain why it is hazardous to add cold water to a tray containing molten wax at a high temperature. (7 marks)

5. HKCEE 2001 Q7b For environmental reasons, the Hong Kong Government has launched a plan for taxis to switch from using

diesel to using liquefied petroleum gas (LPG). (i) Both LPG and diesel are petroleum products. State the origin of petroleum. (ii) With reference to their chemical constituents, explain why LPG is a cleaner fuel than diesel. (iii) State ONE problem that may occur in the initial stage in launching this plan.

(5 marks)

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6. HKCEE 2003 Q7b Cracking is an important process in petrochemical industry.

(i) What is the meaning of the term ‘cracking’? (ii) Account for the importance of cracking in petrochemical industry. (iii) Octane (C8H18) is used in an experiment to study cracking in a school laboratory. Cracking of octane gives a mixture of products, some of which are gases. Draw a labelled diagram for the set-up used in the experiment, including the collection of the gaseous products. (iv) One of the reactions involved in the cracking of octane gives two hydrocarbons, each containing the same number of carbon atoms. (1) Write the chemical equation for this reaction. (2) Suggest a chemical test to distinguish the two hydrocarbons from each other.

(9 marks)

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7. HKCEE 2007 Q2 A student performed an experiment to crack paraffin oil and collect the gaseous products by using a boiling

tube. (a) Draw a labelled diagram to show how this experiment can be performed in the laboratory.

(3 marks) (b) (i) The student added a few drops of bromine water into the boiling tube containing the

gaseous products. The brown colour of bromine water disappeared immediately. Why? (ii) The student then dropped more bromine water into the boiling tube until the brown colour

of the bromine water persisted. After about 10 minutes, the brown colour disappeared. Why? (4 marks)

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8. HKCEE 2008 Q7 Crude oil can be separated into different products such as petrol, diesel oil and fuel oil by a process called

‘A’. The fuel oil obtained can then be converted into smaller molecules by another process called ‘B’. (a) Name process A and process B. (2 marks) (b) (i) Explain whether petrol or diesel oil has a higher viscosity. (ii) Explain whether petrol or diesel oil is a cleaner fuel.

(2 marks)

(c) (i) Suggest one importance of process B in industry. (ii) One of the compounds in fuel oil is 5828HC , which can be converted into smaller molecules as

shown in the following equation.

(1) Suggest a possible structure of D, and state its systematic name. (2) Suggest a chemical test to distinguish D from 4220HC , and state the expected

observation. (5 marks)

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Pollutions 9. HKCEE 1999 Q3

The illustration below shows the exhaust from a motor car using unleaded petrol:

(b) Explain why the exhaust contains carbon monoxide. (c) (1) Write TWO chemical equations for the formation of acid rain from nitrogen oxides.

(2) State ONE undesirable effect of acid rain. (d) State ONE health hazard associated with particulates. (e) Suggest ONE other pollutant that may be found in the exhaust. (f) Suggest a device that can be installed in the motor car to reduce the emission of carbon monoxide and

nitrogen oxides. (7 marks)

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10. HKCEE 2003 Q9c Organic wastes can be used as an alternative energy source. Under suitable conditions, the wastage can be

digested by bacteria to give a gaseous mixture containing a high proportion of methane. Methane can be used as a fuel. (i) Suggest ONE organic waste that can be used for this purpose. (ii) Write the chemical equation for the complete combustion of methane. (iii) Suggest ONE advantage of using organic wastes as an alternative energy source. (iv) Suggest ONE reason why organic wastes are not yet widely used as an energy source.

(4 marks)

11. HKCEE 2004 Q4 Acid rain is a serious environmental problem. Discuss the formation of acid rain in relation to human

activities, and suggest possible ways to reduce its formation. (9 marks)

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12. HKCEE 2006 Q6 Carbon dioxide and methane are two major greenhouse gases in the atmosphere. The table below shows the

average concentrations of the two gases in the atmosphere in 1900 and in 2000.

(a) Suggest TWO reasons why there was a large increase in concentration of carbon dioxide in the atmosphere in the past ten decades.

(2 marks) (b) Suggest ONE reason why there was a large increase in concentration of methane in the atmosphere in

the past ten decades. (1 mark)

(c) The presence of greenhouse gases in the atmosphere is important to life on Earth. However, too much greenhouse gases in the atmosphere can cause global warming, which may lead to severe environmental consequences. (i) State the importance of greenhouse gases to life on Earth. (ii) State ONE severe environmental consequence associated with global warming. (iii) Suggest ONE possible way to prevent further increase in the concentration of each of the

following greenhouse gases in the atmosphere without sacrificing our present standard of living: (I) carbon dioxide (II) methane

(4 marks)

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Homologous series 13. HKCEE 2005 Q5 Both pentane (C5H12) and octane (C8H18) are members of the same homologous series.

(a) Using pentane and octane as examples, illustrate TWO characteristics of the members of a homologous series.

(4 marks) (b) Which compound, pentane or octane, will burn with a more sooty flame? Explain your answer.

(2 marks) (c) Draw TWO structures which have the same molecular formula C5H12.

(2 marks)

Alkanes and Alkenes 14. HKCEE 1998 Q2 For each of the following experiments, state the expected observation and write a relevant chemical equation. (a) Ethene is passed into an acidified potassium permanganate solution.

(b) A mixture of butane and bromine vapour is exposed to diffused sunlight. (4 marks)

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15. HKCEE 2002 Q5 Using alkenes as an example, describe the characteristics of members of a homologous series.

(9 marks)

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16. HKCEE 2006 Q1b A student suggested using the set-up shown below to separate hex-1-ene from a mixture of hex-1-ene and

hexane. (At atmospheric pressure, the boiling points of hex-1-ene and hexane are 64°C and 69°C respectively.)

(i) Explain why it is dangerous to use the above set-up to carry out the experiment. Suggest a modification to the set-up so that the experiment can be carried out safely.

(ii) After the set-up has been modified as suggested in (i), can it be used to separate hex-1-ene from hexane effectively? Explain your answer.

(iii) Suggest a chemical test to distinguish hex-1-ene from hexane. (5 marks)

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Alkanols, Alkanoic Acids and Esters 17. HKCEE 1994 Q6b The following paragraph was taken from a student’s laboratory report: ‘A mixture of ethanol, ethanoic acid and several drops of concentrated sulphuric acid was heated under reflux

for some time. The resulting mixture was then cooled and poured into a beaker containing some saturated sodium chloride solution.’ (i) Draw a labeled diagram of the experimental set-up used for heating the mixture under reflux. (ii) Why is it necessary

(1) to use concentrated sulphuric acid in the above experiment? (2) to heat the mixture under reflux?

What would be observed when the resulting mixture was poured into the saturated sodium chloride solution?

(7 marks)

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18. HKCEE 1995 Q7b The following flow diagram shows the conversion of a compound X to an acid Y.

X can rapidly decolourize a solution of bromine in 1,1,1-trichloroethane.

(i) What is X? Name the industrial process by which X is converted to ethanol. # (i) Write a chemical equation for the reaction between X and bromine (ii) (1) Give the systematic name of Y.

(2) Draw a labeled diagram of the laboratory set-up for the conversion of ethanol to Y.

(v) Ethanol can be detected in the breath of a drunken driver. Suggest ONE chemical test to show the presence of ethanol in his breath and state the observable change produced by the test.

(9 marks)

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19. HKCEE 1998 Q9 A student used the following set-up to prepare propanoic acid:

(i) Name apparatus X. (ii) Explain why some pumice stones were added to the reaction mixture before heating. (iii) Write the chemical equation for the reaction involved. (iv) Suggest a method to obtain propanoic acid from the reaction mixture.

The student used the propanoic acid obtained to carry out the following experiment:

(v) Why is a water bath, instead of a naked flame, used for heating the test tube and its contents?

(vi) (1) State TWO observable changes when the contents of the test tube were added to the sodium carbonate solution. (2) Give the systematic name of the carbon compound formed in the experiment.

(8 marks)

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20. HKCEE 2002 Q6c Ethyl ethanoate is an ester. It can be prepared by heating a mixture of ethanoic acid and ethanol under reflux

in the presence of a catalyst. (i) What is the catalyst used in the preparation? (ii) Draw a labeled diagram of the set-up used for heating the mixture under reflux. (iii) Ethyl ethanoate is commonly used as a solvent. Explain why ethyl ethanoate can dissolve iodine but cannot dissolve sodium iodide. (iv) Which ONE of the following hazard warning labels should be displayed on a bottle of ethyl ethanoate?

(v) Draw the structure of another ester which has the same molecular formula as ethyl ethanoate, and give its systematic name.

(9 marks)

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21. HKCEE 2004 Q8c A policeman suspected a car driver to have drunk an excessive amount of alcoholic drinks, and used a

dichromate breathalyser to conduct a test on the driver’s breath. The result was positive.

(i) State the principle underlying the test of ethanol using a dichromate breathalyser. (ii) The driver claimed that he had just rinsed his mouth using ethanol-containing mouthwash.

Without using other instruments, suggest how the policeman could check whether the driver’s claim was valid or not. Explain your answer.

(4 marks)

22. HKCEE 2004 Q9b An ester can be prepared by heating an alkanol with an alkanoic acid under reflux in the presence of

concentrated sulphuric acid.

(i) Draw a labelled diagram to show the set-up used in heating the reaction mixture under reflux. (ii) Suggest ONE reason why it is necessary to heat the mixture under reflux.

(3 marks)

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23. HKCEE 2006 Q2 X, Y and Z are organic compounds. The flow diagram below shows the conversion of X to Z.

(a) Z has a pleasant smell and its molecular formula is C4H8O2. Draw the structure of Z. (b) To which homologous series does Y belong? (c) Give the systematic name of X. (d) State the expected observation when X reacts with acidified potassium dichromate solution. (e) State the function of concentrated sulphuric acid in the reaction of Y with methanol.

(5 marks)

24. HKCEE 2008 Q9 Outline the steps showing how a sample of ethyl ethanoate ( 323 CHCOOCHCH ) can be prepared and

isolated in the laboratory by using ethanol, concentrated sulphuric acid, 0.1 M potassium dichromate solution, quickfit apparatus, heating source, and other common apparatus.

(Diagrams, chemical equations, and detailed descriptions in setting up of apparatus are NOT required.) (9 marks)

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25. HKCEE 2009 Q8

A student attempted to oxidise ethanol to ethanoic acid using the set-up shown below.

(a) Suggest an oxidising agent that can be used. (b) State one advantage of using a hot water bath over direct heating with a Bunsen burner in carrying out the

experiment. (1 mark)

(c) The student failed to obtain ethanoic acid even after a long period of time. The student then used Quickfit apparatus to perform the experiment. After some time, ethanoic acid was finally obtained.

(l mark) (i) Draw a labelled diagram to show how to set up Quickfit apparatus for carrying out the

experiment. (ii) Explain why ethanoic acid could finally be obtained.

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26. HKCEE 2010 Q3 A is an alkanol with three carbon atoms and one oxygen atom in its molecule. A reacts with acidified potassium

dichromate solution to form compound B. In the presence of a small amount of concentrated sulphuric acid, A reacts with B to form compound C. C can be separated from the reaction mixture and has a pleasant smell.

(a) Write the structural formulae of A, B, and C. (3 marks)

(b) State the expected observation for the reaction of A with acidified potassium dichromate solution. (1 mark)

(c) Suggest a method to separate C from the reaction mixture. (1 mark)

(d) A compound has the same molecular formula as A but a different structure from A. Suggest a structural formula for this compound.

(1 mark)

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Plastics 27. HKCEE 1994 Q3

The following diagrams show some items made of synthetic polymers.

(a) Which of the above items is most likely to be made of thermosetting plastics? Explain your answer. (b) Name one synthetic polymer which is suitable for making the plastic bag. (c) Suggest a suitable moulding method used in making the electric switch. (d) Terylene, the polyester fibre used for making the shirt is synthesized from ethane-1,2-diol,

HOCH2CH2OH and benzene-1,4-dicarboxylic acid, HOOCC6H4COOH. (i) Name the type of polymerization involved in the synthesis of terylene. (ii) Write a repeating unit of terylene.

(6 marks)

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28. HKCEE 1996 Q7b The flow diagram below shows the three key stages involved in the production of polypropene bottles from

crude oil.

(i) What is the process involved in obtaining heavy oil from crude oil in Stage I?

(ii) (1) Draw the structure of monomer A.

(2) What are the TWO main processes involved in the production of monomer A from heavy oil in Stage II?

(iii) What are the TWO main processes involved in the production of polypropene bottles from monomer A in Stage III?

(iv) Suggest ONE reason why the disposal of polypropene wastes can cause pollution problems. (v) Polypropene wastes can be recycled by melting and remoulding.

(1) What preliminary treatment of the polypropene wastes is required before recycling?

(2) Name ONE plastic which cannot be recycled by melting and remoulding. (9 marks)

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29. HKCEE 1997 Q1c For each of the tasks listed in the table below, decide which substance on the right is the best to use to

accomplish the task. Explain your answer in each case.

Task Substances

To make feeding bottles for babies

polyethene, polystyrene, urea-methanal

(3 marks)

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30. HKCEE 1998 Q7b Polyvinyl chloride (PVC) is a plastic which has a wide range of uses.

(i) Write the chemical equation for the formation of PVC from its monomers.

(ii) Plastic products made of PVC may vary greatly in rigidity.

(2) Give ONE flexible product made of PVC. (3) Give ONE rigid product made of PVC. (4) Explain whether PVC is suitable for making electric sockets or not.

(iii) Incineration of PVC wastes produces hydrogen chloride which causes air pollution. (1) State ONE harmful effect of the discharge of hydrogen chloride into the atmosphere. (2) Suggest how hydrogen chloride can be removed from incinerator flue gas prior to its discharge to

the atmosphere. (3) Suppose that all the chlorine in PVC is converted to hydrogen chloride upon incineration.

Calculate the volume of hydrogen chloride produced, measured at room temperature and pressure, when a plastic waste containing 1000 kg of PVC is incinerated. (You may assume that no other chlorine-containing compounds are present in the waste.)

(Relative atomic masses: H = 1.0, C = 12.0, Cl = 35.5; molar volume of gas at room temperature and pressure = 24.0 dm3)

(9 marks)

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31. HKCEE 1999 Q1 Each of the tasks listed in the table below can be accomplished by using material A or B.

Material Task

A B

(a) To make water pipes polyvinyl chloride iron

(b) To make lenses perspex glass

(c) To make shopping bags polyethene paper

In each case, state an advantage of

(i) using A over B to accomplish the task. (ii) using B over A to accomplish the task.

(You are not required to consider the price of the materials.)

(6 marks)

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32. HKCEE 2000 Q7b Polystyrene can be prepared in the laboratory by heating a mixture of styrene and kerosene under reflux.

(i) Draw a labeled diagram of the set-up used for heating the mixture under reflux. (ii) Suggest ONE safety precaution that should be taken when heating the mixture. Explain your answer. (iii) Styrene has the following structure:

C6H5CH=CH2 (1) What characteristic in the structure of styrene enables it to act as a monomer? (2) Write the chemical equation for the polymerization.

(iv) Disposable lunch boxes are commonly made of expanded polystyrene. (1) Suggest ONE reason why polystyrene should be expanded before it is used to make disposable

lunch boxes. (2) State whether you agree with the following statement. Explain your answer.

‘Landfilling is better than incineration for the disposal f polystyrene wastes.’ (8 marks)

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33. HKCEE 2001 Q7a Polyethene is used in making shopping bags and its monomer is ethene.

(i) Draw the electronic diagram of ethene, showing electrons in the outrmost shells only.

(ii) Name the type of polymerization involved in the production of polyethene.

(iii) State ONE property of polyethene that makes it suitable for making shopping bags.

(iv)(1) Suggest ONE way to dispose of polyethene wastes. (2) Give ONE advantage and ONE disadvantage of the way you have suggested in (1).

(6 marks)

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34. HKCEE 2002 Q8c Polyethylene terephthalate (PET) is a polymer which is commonly used in making plastic bottles for fizzy

drinks. PET has the following repeating unit:

(i) PET is formed by condensation polymerization. What is meant by the term ‘condensation polymerization’ ?

(ii) PET is a polyester formed from two monomers. Draw the structures of the monomers.

(3 marks)

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35. HKCEE 2003 Q5 Plastic wastes cause environmental problems in modern cities. Suggest possible ways of treating plastic

wastes, and discuss their advantages and disadvantages.

(9 marks)

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36. HKCEE 2004 Q6c Pyrolysis is one of the methods commonly used for treating plastic wastes. During pyrolysis, plastic wastes

are decomposed at high temperature in the absence of air to give a mixture of products, including methane and ethene.

(i) Explain why it is necessary to carry out the pyrolysis in the absence of air. (ii) Suggest a method that can be used to separate methane from other pyrolysed products. (iii) Give ONE major use of methane and ONE major use of ethene in industry. (iv) (1) Suggest another method which is commonly used for treating plastic wastes. (2) For each of the two methods, pyrolysis and the method you have suggested in (1) above, state ONE

advantage. (7 marks)

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37. HKCEE 2005 Q6 (a) Polystyrene is a plastic with a wide range of uses. It has the following structure :

(i) Draw the structure of styrene, the monomer of polystyrene. (ii) Suggest why polystyrene does NOT have a constant relative molecular mass.

(2 marks) (b) Polystyrene can be prepared from styrene using the set-up shown below:

(i) Name apparatus A. (ii) Suggest, with explanation, a safety precaution that should be taken in the preparation. (iii) Name the type of polymerisation involved in the formation of polystyrene from its monomer.

(4 marks) (c) Plastics are very useful materials. Many objects previously made with metals are now made with plastics.

For each of the following objects, suggest ONE advantage of using plastics over using metals in making the object.

(i) the casing for an electric rice cooker (ii) a drainage pipe (iii) a helmet for a soldier

(3 marks)

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38. HKCEE 2006 Q11 Plastics can be classified into thermoplastics and thermosetting plastics according to their thermal properties. (a) Explain, in terms of bonding and structure, why thermoplastics and thermosetting plastics before

differently upon heating. (3 marks)

(b) Polyethene (PE) is a thermoplastic commonly used in making shopping bags. Such bags are durable. (i) Write the chemical equation for the formation of PE from its monomer. (ii) Explain, in terms of bonding, why objects made of PE are durable.

(2 marks) (c) Some scientists suggested using polylactic acid (PLA) instead of PE to make shopping bags as this can

help reduce environmental problems. PLA is a polyester made from lactic acid, which has the following structure:

(i) Identify the functional groups in lactic acid. (ii) Write the repeating unit of PLA. (ii) Explain, in chemical terms, why the disposal of PLA poses less harm to the environment than

that of PE. (4 marks)

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39. HKCEE 2007 Q8 (a) Teflon is a plastic that can be used to make artificial hip joints. Teflon is an addition polymer of linear

structure consisting of carbon and fluorine only. The ratio of the number of carbon atoms to the number of fluorine atoms in the polymer is 1 : 2.

(i) Draw a portion of the teflon structure with 10 carbon atoms. (ii) Write the repeating unit of teflon, and suggest a possible monomer of teflon.

(3 marks) (b) Nylon is a polymer that can be used to make carpets . A portion of the nylon structure is shown below:

(i) With reference to the given structure, explain whether nylon is a thermoplastic or a thermosetting

plastic.

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(ii) Suggest one reason why recycling of used carpets to recover nylon is difficult. (iii) State one disadvantage of disposing of nylon carpets by incineration.

(3 marks)

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40. HKCEE 2008 Q8 The active ingredient of a superglue has the following structure:

Superglue can join objects together quickly through the polymerization of the active ingredient in the

presence of water vapour. (a) Name the type of polymerization that the active ingredient undergoes. (b) Write a chemical equation for the polymerization involved. (c) Assuming that the active ingredient comes from esterification of two compounds, write the structural

formulae of these two compounds. (d) In addition to putting back the cap for the superglue that remains after use, what storage method could help

extend the lifetime of the superglue? (5 marks)

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41. HKCEE 2010 Q12 Polyethylene terephthalate (PET) is a thermoplastic that can be used to make soft drink bottles. PET is

formed from polymerisation of two different monomers and has the following structure :

(a) Write the structural formulae of two monomers that can be polymerised to PET.

(2 marks)

(b) In terms of bonding and structure, explain why PET is a thermoplastic. (1 mark)

(c) Name the type of the above polymerisation and give the reason. (2 marks)

(d) Suggest a moulding method that can be used to make soft drink bottles from PET beads. (1 mark)

(e) PET bottles CANNOT be used to store drain cleaners containing concentrated sodium hydroxide solution because PET reacts with strong alkalis.

(i) What is the reaction involved ? (ii) Write the structural formula of one of the products of the reaction.

(2 marks)

(f) Polypropene (PP) can be used to make bottles for storing drain cleaners containing strong alkalis. Write a chemical equation for the polymerisation to form PP.

(1 mark)

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Detergents 42. HKCEE 1995 Q9a Sodium hydroxide can be used as a raw material in the manufacture of both soapy and soapless detergents.

(i) Briefly describe how a soapy detergent can be prepared from a vegetable oil in a school laboratory. (ii) The formula of a certain soapy detergent is CnH2n+1COONa and its formula mass is between 300 and 310. Calculate the value of n. (iii) The structure of a certain soapless detergent is shown below:

(1) What other raw materials, apart from sodium hydroxide, are required in the manufacture of this

soapless detergent?

(2) Give ONE advantage and ONE disadvantage of using this soapless detergent for domestic cleaning compared with using a soapy detergent.

(Relative atomic masses: H = 1.0, C = 12.0, O = 16.0, Na = 23.0) (10 marks)

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43. HKCEE 2000 Q6c Explain the following statements:

(i) In cold weather, a person trying to warm up a room with a coal fire soon gets dizzy. (ii) Detergents can be used to clean up oil spillage in the sea.

(5 marks)

44. HKCEE 2001 Q6 (a) Soap powder usually contains washing soda, a hydrated form of sodium carbonate, which can help

reduce the hardness of water. (i) Explain why soap does not function well in hard water. (ii) With the help of an ionic equation, explain why washing soda can help reduce the hardness of

water. (4 marks)

(b) In an experiment, 0.933g of a sample of washing soda (Na2CO3.xH2O) was dissolved in some distilled water. The solution was titrated against 0.258M hydrochloric acid with methyl orange as indicator. 25.4 cm3 of the acid was required for the completion of the following reaction:

Na2CO3 + 2HCl→ 2NaCl + H2O + CO2 (i) From the titration result, calculate the number of moles of sodium carbonate in the sample of

washing soda. (ii) Deduce the value of x in the formula of the washing soda. (iii) State the colour change at the end-point of the titration. (iv) Briefly describe the procedure that should be followed to prepare a burette containing the

hydrochloric acid for the titration. (Relative atomic masses: H = 1.0, C = 12.0, O = 16.0, Na = 23.0)

(9 marks) (c) (i) State the structural characteristics of a detergent. Hence, explain why detergents can remove oily

dirt. (ii) Suggest, with explanation, an environmental consequence associated with the discharge of waste

water containing detergents into rivers and lake. (5 marks)

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45. HKCEE 2004 Q7b The structure of a detergent is shown below:

CH3(CH2)16CO2− Na+

(i) This detergent, when shaken with a mixture of water and paraffin oil, gives an emulsion. With reference to the structure of the detergent, explain the phenomenon.

(ii) An oil tanker was wrecked and split a lot of crude oil in the sea. State whether this detergent is suitable for treating the oil spill. Explain your answer.

(5 marks)

46. HKCEE 2005 Q11 Vegetable oils are esters formed from carboxylic acids with long carbon chains. Although vegetable oils

have high calorific values comparable to diesel, they are not used directly as fuel in cars. One of the reasons is due to their high viscosity. By heating with methanol in the presence of sodium hydroxide solution, vegetable oils can be converted to less viscous esters, methyl carboxylates. These methyl carboxylates can be used to substitute diesel as fuel in cars.

(a) The equation below shows the conversion of vegetable oil X to methyl carboxylate Y and alcohol Z:

(i) Draw the structure of Z. (ii) Suggest why Y is less viscous than X. (iii) Sodium hydroxide solution acts as a catalyst in this conversion. What is the meaning of the

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term ‘catalyst’? (iv) Y and Z are immiscible liquids. Suggest a method to separate Y and Z from their mixture.

(5 marks) (b) The term ‘biodiesel’ refers to the methyl carboxylates obtained from vegetable oils. Suggest TWO

reasons why biodiesel is considered a more environmentally-friendly fuel than diesel. (2 marks)

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47. HKCEE 2007 Q13 Discuss the similarities and differences between soapy detergents and soapless detergents with reference to

their raw materials, structures and properties. (9 marks)

48. HKCEE 2009 Q12

The procedures in an experiment are summarised below. A mixture of castor oil and sodium hydroxide solution was heated gently with stirring for 15

minutes. After cooling down the mixture, a white solid X was obtained upon adding a colourless solution Y. X was then separated out and washed with distilled water.

A small amount of X was put in a test tube containing a mixture of water and a few drops of oil. The contents of the test tube were thoroughly shaken and the observation was recorded. (a) Name the type of reaction involved when the mixture of castor oil and sodium hydroxide

solution was heated. (1 mark)

(b) Suggest what Y would be. (1 mark)

(c) The structure of a main ingredient of castor oil is shown below.

Suggest a structure for X. (1 mark)

(d) State the expected observation while shaking the test tube. Explain your answer.

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(3 marks) (e) Suggest a title for the experiment that reflects its objectives.

(2 marks) (f) If X is dissolved in water to form an aqueous solution, what would be observed in shaking a

mixture of this solution and lime water? (1 mark)

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Miscellaneous 49. HKCEE 1999 Q9b

Cracking of naphtha gives alkane X (relative molecular mass 44), alkene Y (relative molecular mass 42) and other products. (i) What is the meaning of the term ‘cracking’? (ii) Suggest a chemical test to distinguish between X and Y. (iii) Deduce the molecular formula of Y. (iv) Y can be used as a starting material for the production of plastic Z.

(1) Write the chemical equation for the formation of Z from Y. (2) Suggest how plastic cups can be made from Z.

(v) Suggest an advantage and a disadvantage of using plastic wastes as an energy source. (Relative atomic masses: H = 1.0, C = 12.0)

(10 marks)

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50. HKCEE 2007 Q7 This question involves how to distinguish four unlabelled test tubes, each containing one of the following

colourless liquids:

methanol, concentrated sodium hydroxide solution, distilled water, hexane

(a) By heating a small amount of each of the colourless liquids to dryness, ONE of the liquids can be

distinguished. Suggest which liquid can be distinguished, and state the observation involved. (2 marks)

(b) By applying a flame directly to a small amount of each of the colourless liquids, TWO of the liquids would catch fire.

(i) Suggest which two liquids would catch fire. (ii) For the two liquids that would catch fire, the observations involved during combustion are

different. Suggest the difference in these observations, and explain your answer. (iii) Without using other chemicals apart from the above colourless liquids, suggest another

method to distinguish the two liquids that would catch fire. State the expected observation. (Smelling is not accepted.)

(4 marks)

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51. HKCEE 2007 Q12 Organic compound Z contains carbon, hydrogen and oxygen only. Analysis of Z gives the following

results:

(I) 1.0 g of Z contains 0.401 g of carbon, 0.068 g of hydrogen and 0.531 g of oxygen. (II) 1.0 g of Z, upon complete vaporisation, occupies 400 cm3 at room temperature and pressure. (III) There are no observable changes when potassium carbonate solution is added to Z. (IV) Brown colour of bromine remains unchanged when several drops of bromine in organic solvent are

added to Z. (Molar volume of gas at room temperature and pressure = 24 dm3)

(a) Calculate the empirical formula of Z. (2 marks)

(b) Deduce the molecular formula of Z. (2 marks)

(c) (i) Suggest a possible structure of Z. Explain your answer. (ii) Give the systematic name for the compound represented by the structure you suggested in

(i). (2 marks)

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52. HKCEE 1997 Q7b The structures of five compounds, I, II, III, IV and V, are shown below:

In the above structures, represents a saturated hydrocarbon chain containing 1 to 6 carbon atoms and

represents a saturated hydrocarbon chain containing 12 to 20 carbon atoms. (i) Which compound can be used to make an addition polymer? Write a chemical equation to represent the

addition polymerization.

(ii) Which TWO compounds can be used to make a condensation polymer? Draw the repeating unit of the polymer formed.

(iii) Upon heating with sodium hydroxide solution, one of these compounds produces a soapy detergent. (4) What is this compound? (5) Draw the structure of the soapy detergent produced. (6) Briefly explain the emulsifying action of the detergent when it is used to remove greasy dirt.

(10 marks)

nss chemistry part 5 & 11 chemistry of carbon compounds

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