Unit 2 - Alcohols
Unit 2 - Jan 2009
Q1.
 Which of these is a tertiary alcohol?
   A     3-methylpentan-2-ol
   B     Pentan-2-ol
   C     Pentan-3-ol
   D     2-methylpentan-2-ol
(Total for question = 1 mark)

Q2.
Ethanoic acid is used industrially in the manufacture of polymers and glues and also in
 the food industry as an acidity regulator.
 It can be synthesized in the laboratory by the reaction of ethanol with excess sodium
 dichromate(VI) solution, acidified with concentrated sulfuric acid.  Ethanol is placed
 in a suitable flask along with some anti-bumping beads.  The concentrated sulfuric
 acid is then added a drop at a time.  The sodium dichromate(VI) solution is then added
 a drop at a time causing the mixture to boil spontaneously.  When the addition of the
 sodium dichromate(VI) solution is complete, the mixture is heated under reflux for
 approximately 15 minutes.  The ethanoic acid formed can then be separated from the
 reaction mixture.

Ethanoic acid can be produced industrially by the CativaTM process.  Methanol, which
 can be obtained from wood, is reacted with carbon monoxide in the presence of an
 iridium catalyst.

(a)  (i)   Balance the half-equation for the reduction of dichromate(VI) ions.
(1)

(ii)   The half-equation for the oxidation of ethanol is

Use this and your answer to (a)(i) to write a full equation for the overall reaction
 between acidified dichromate(VI) ions and ethanol.  State symbols are not
 required.
(2)

(b)  (i)   Why are the concentrated sulfuric acid and sodium dichromate(VI) added a drop
              at a time in the laboratory process?
(1)
 ............................................................................................................................................. 
 (ii)   Draw a labelled diagram of the apparatus that could be used to heat the mixture
        under reflux.
(3)

(iii)   What colour would the mixture be after it was heated under reflux?
(1)
 ............................................................................................................................................. 
(c)  A solution containing both water and ethanoic acid is produced by distillation of the
       final reaction mixture.
(i)   Explain why the other products and any excess reactants are left behind in the
       distillation flask.
(1)
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(ii)   Suggest a method to separate pure ethanoic acid, boiling temperature 118°C,
        from the water.
(1)
 ............................................................................................................................................. 
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(d)  (i)   In the CativaTMprocess what effect, if any, would increasing the pressure have
              on the yield of ethanoic acid?  Justify your answer.
(2)
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(ii)   Suggest TWO reasons why it might be difficult, or undesirable, to produce
        ethanoic acid in industry by scaling up the laboratory process.
(2)
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*(e)  An alternative industrial process for the production of ethanoic acid is the oxidation
         of butane using a transition metal catalyst at 150°C and 55−60 atm.

Evaluate the 'greenness' and sustainability of the two industrial processes.

 Suggest TWO additional pieces of information that would help you make a more
 informed decision.
(6)
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(Total for question = 20 marks)

Unit 2 - Jun 2009
Q3.

(a)  Draw a diagram to show the most significant intermolecular force between an
       ethanol molecule and a water molecule.  Label the bond angle between the molecules
       and state its value.
(2)

(b)  The student proposed to set up the apparatus as shown below to carry out the
        distillation to try to separate the ethanol from water.
        There are three errors with the set-up.  Draw a circle around each error.
        Describe what effect these errors would have if the student attempted to carry out the
        separation as shown.
        [Clamps are not shown in the diagram but you can assume the apparatus is supported
        adequately.]
(6)

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(c)  If a balance is accurate to two decimal places was used to record the mass of ethanol
       collected, what would be the percentage error due to the balance readings if the total
       mass of ethanol collected was 20.10 g?
(1)

(d)  Suggest a suitable drying agent to absorb the water remaining with the ethanol after
        distillation.  Describe how you would use it to produce a dry sample of ethanol.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 

(e)  Describe a chemical test you could carry out to confirm the presence of the
       −OH group in ethanol.  What result would you expect to see?
(2)
Test
 ............................................................................................................................................. 
 ............................................................................................................................................. 
Result
 ............................................................................................................................................. 
(f) *(i)  Explain what is meant by a carbon neutral fuel.
(2)
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*(ii)  Suggest TWO reasons why these biofuels may not be carbon neutral and
         describe TWO effects that large scale production of biofuels may have on
         society.  Which of the three biofuels do you think is the most sustainable?
         Justify your choice.
(5)
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(Total for question = 20 marks)
Q4.
What is the correct systematic name for the alcohol shown below?

   A     hexan-4-ol
   B     hexan-2-ol
   C     pentan-4-ol
   D     pentan-2-ol
(Total for question = 1 mark)

Unit 2 - Jan 2010
Q5.
 Butan-1-ol and three other alcohols, X, Y and Z, are isomers.
(a)  (i)  Give TWO observations you would make when any one of the alcohols reacts
             with sodium.
(2)
 ............................................................................................................................................. 
............................................................................................................................................. 
(ii)  Give the molecular formula of the organic product of the reaction.
(1)
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(b)  Isomer X does not react with a mixture of potassium dichromate(VI) and sulfuric acid.
Draw the displayed formula of X and name it.
(2)

Name
 ............................................................................................................................................. 
(c)  When isomer Y is heated under reflux with a mixture of potassium dichromate(VI)
       and sulfuric acid, it forms 2-methylpropanoic acid.
Deduce the structural formula of the alcohol Y.
(1)

(d)  (i)  Isomer Z reacts with a mixture of potassium dichromate(VI) and sulfuric acid to
             form a compound Q, which does not react with Fehling's or Benedict's solution.
Deduce the structural formula of the alcohol Z.
(1)

(ii)  What would be the principal difference between the infrared spectrum of Q and
        the infrared spectrum of 2-methylpropanoic acid?
You are not expected to quote absorption values.
(1)
 ............................................................................................................................................. 
 (e)  One of the isomers, X, Y or Z can be converted to 2-chlorobutane.
What reagent would you use to carry out this conversion?
(1)
 ............................................................................................................................................. 
(f)  (i)  2-chlorobutane reacts with silver nitrate in a mixture of ethanol and water as a
            solvent. What would you see when the reaction occurred?
(1)
 ............................................................................................................................................. 
*(ii)  Both ethanol and water contain hydrogen bonds. By considering the hydrogen
         bonding on these two solvents, suggest why 2-chlorobutane is more soluble in
         ethanol than in water.
(2)
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(Total for question = 12 marks)

Q6.

*(a)  Why are the bonds within a layer of carbon atoms in graphite stronger than the
          bonds between the layers of carbon atoms?
(2)
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(b)  The data below gives the relative electrical conductivity of a pure graphite crystal.

Explain why the relative electrical conductivity of graphite differs with direction.
(2)
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(c)  Suggest why the strength of the bond between the layers in graphite would increase
        if some carbon atoms were replaced with nitrogen atoms.
(2)
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 ............................................................................................................................................. 
(d)  Suggest ONE benefit of using a light activated catalyst for the new process.
(1)
 ............................................................................................................................................. 
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(e)  The liquid fuel, methanol, is made by reacting carbon monoxide with hydrogen.
Write an equation for this reaction. State symbols are not required.
(1)

*(f)  Benzene, which is needed for the new process of breaking down carbon dioxide, can
         be made from coal. It is now usually made by catalytic treatment of one fraction of
         crude oil at temperatures of around 500 °C and 20 atmospheres pressure.
Suggest the benefits and disadvantages of breaking down carbon dioxide using
 benzene and the catalyst as described in the passage. You should consider

·	the energy and resources needed
·	the effects on the atmosphere
·	whether it is a beneficial method for producing energy compared to direct
 use of fossil fuels. 
(6)
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(g)  Carbon exists in forms other than graphite. Nanotubes are rolls of graphite layers,
       and fullerenes are cages of carbon atoms. Both nanotubes and fullerenes can
       trap other substances in their structures, and fullerenes can be coated with other
       substances.
Give ONE application of carbon nanotubes or fullerenes which exploits this
 behaviour.
(1)
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(Total for question = 15 marks)

Unit 2 - Jun 2010
Q7.
 The best method of converting ethanol, C2H5OH, into iodoethane, C2H5I, is to
   A     heat iodine and ethanol under reflux.
   B     react ethanol and potassium iodide in the presence of dilute acid.
   C     heat potassium iodide and ethanol with concentrated sulfuric acid.
   D     heat red phosphorus, ethanol and iodine under reflux.
(Total for question = 1 mark)

Q8.
 (a)  Propene, C3H6, reacts with hydrogen bromide, HBr, in an electrophilic addition reaction.
2-bromopropane is formed as the major product.

(i)  Complete the mechanism for the reaction, using 'curly arrows' where appropriate. Show clearly the structure of the intermediate carbocation formed.
(3)

(ii) Draw the structure of the alternative carbocation that can be formed in the reaction between propene and hydrogen bromide.
(1)

(b)  Four isomers, each with the molecular formula C4H10O, are shown below.
Isomer A:     CH3CH2CH2CH2OH
Isomer B:     CH3CH2CH(OH)CH3
Isomer C:     (CH3)3COH
Isomer D:     CH3CH(CH3)CH2OH
(i)  Which isomer is a secondary alcohol? Justify your answer.
(2)
 ............................................................................................................................................. 
............................................................................................................................................. 
(ii)  Which isomer is resistant to oxidation when heated with acidified potassium
       dichromate(VI)? Justify your answer in terms of the structure of the isomer.
(2)
 ............................................................................................................................................. 
............................................................................................................................................. 
(iii)  Which isomer can be oxidized to a ketone? Draw the displayed formula of the
        ketone produced.
(1)
 ............................................................................................................................................. 
(iv)  Which isomers can be oxidized to an aldehyde?
(1)
 ............................................................................................................................................. 
(v)  Phosphorus(V) chloride (phosphorus pentachloride), PCl5, is used to test for the presence of an −OH group.

       What would you expect to see when any of the above four isomers, A, B, C or D, are reacted with phosphorus(V) chloride?
(1)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
(vi)  Complete the equation for the reaction shown below. State symbols are not
        required.
(2)

(Total for question = 13 marks)
Unit 2 - Jan 2011
Q9.
 This question is about methanol, CH3OH, and ethanol, CH3CH2OH.
(a) (i) Draw a dot and cross diagram for methanol, showing outer electrons only.
(1)

     (ii) Give the approximate values for the HCH and COH bond angles in methanol.
                  Justify your answers.
(4)
HCH angle .........................
Justification
 ............................................................................................................................................. 
............................................................................................................................................. 
COH angle .........................
Justification
 ............................................................................................................................................. 
............................................................................................................................................. 
     (iii) Using displayed formulae, draw a diagram to show a hydrogen bond between two methanol molecules. On your diagram, show the bond angle around the hydrogen atom of the hydrogen bond and give its value.
(2)

(b) Methanol reacts with sodium.
(i) State what you would observe in this reaction.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
(ii) Write the equation for this reaction. State symbols are not required.
(1)

(c) Ethanol can be used to make ethanal.
(i) Identify, by name or formula, the two chemicals you would use to make ethanal from ethanol in the laboratory.
(2)
 ............................................................................................................................................. 
 (ii) Draw a diagram of the apparatus you would use to prepare ethanal from ethanol in the laboratory and collect the product.
(2)

(iii) Both ethanal and propane have a molar mass of 44 g mol−1, but their boiling temperatures are different.

                    Suggest which substance has the higher boiling temperature. Justify your answer by comparing the intermolecular forces in each compound.
(2)
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(Total for question = 16 marks)
Q10.
Consider the following organic liquids:
A  ethanal
B  ethanol
C  tetrachloromethane
D  trichloromethane

(a) Each liquid is run from a burette. Which liquid would not be deflected significantly by a charged rod?
(1)
   A
   B
   C
   D

(b) Which liquid would react with phosphorus(V) chloride to give a gas which fumes in moist air?
(1)
   A
   B
   C
   D

(c) Which liquid would you expect to have the peak at the greatest mass/charge ratio in its mass spectrum?
(1)
   A
   B
   C
   D

(d) Which liquid has an infrared spectrum with a broad absorption due to hydrogen bonding?
(1)
   A
   B
   C
   D
(Total for question = 4 marks)

Unit 2 - Jun 2011
Q11.
 How many molecular ion peaks (parent ion peaks) occur in the mass spectrum of 1,2-dibromoethane, CH2BrCH2Br?
Assume the only isotopes present are 1H, 12C, 79Br and 81Br.
   A    1
   B    2
   C    3
   D    4
(Total for Question = 1 mark)

Q12.
Propan-1-ol and propan-2-ol are separately oxidized under mild conditions by acidified sodium dichromate(VI) and the product immediately distilled off. What is the oxidation product in each case?

(Total for Question = 1 mark)
Q13.
This question is about ethanethiol, CH3CH2SH. Thiols are like alcohols, but the oxygen atom has been replaced by a sulfur atom. They react in a similar way to alcohols.
(a) (i)   Draw a dot and cross diagram for ethanethiol, showing outer electrons only.
(2)

    (ii)  Give the value for the CSH bond angle in ethanethiol. Justify your answer.
(3)
CSH angle .........................
Justification
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(b) There are hydrogen bonds between ethanol molecules but not between ethanethiol molecules.
      (i)   Explain why the bond angle around the hydrogen atom involved in a hydrogen bond is 180°.
(2)
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      (ii)  Explain why there are no hydrogen bonds between ethanethiol molecules.
(1)
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(c) (i)   Describe the formation of London forces.
(2)
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      (ii)  Explain why the London forces in ethanethiol are stronger than those in ethanol.
(1)
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(d) The reaction of sodium with ethanethiol, CH3CH2SH, is similar to its reaction with ethanol.
      (i)    Suggest one observation you would make when sodium is added to ethanethiol.
(1)
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 ............................................................................................................................................. 
      (ii)   Suggest a balanced equation for this reaction. State symbols are not required.
(1)

(e) Ethanol can be made from bromoethane by reaction with aqueous potassium hydroxide, KOH(aq), under suitable conditions.
      (i)   Write the equation for this reaction. State symbols are not required.
(1)

      (ii)  State the type and mechanism of this reaction.
(2)
Type
 ............................................................................................................................................. 
Mechanism
 ............................................................................................................................................. 
     (iii)  Suggest the formula of a suitable chemical to make ethanethiol from bromoethane.
(1)
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(f) When ethanethiol undergoes complete combustion in air, a gas is produced which is not formed on the complete combustion of ethanol. Identify the gas and suggest why it is damaging to the environment.
(2)
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(Total for Question = 19 marks)

Unit 2 - Jan 2012
Q14.
 Which of the following is a secondary alcohol?
   A  butan-1-ol
   B  butan-2-ol
   C  2-methylpropan-1-ol
   D  2-methylpropan-2-ol
(Total for question = 1 mark)

Q15.
Halogenoalkanes are important intermediates in organic chemistry. The scheme below summarises some important reactions of a halogenoalkane.

(a)  Identify the reagents and any specific conditions required for the reactions in the diagram. (You may assume that a suitable temperature is maintained in each reaction.)
(4)
A
 ............................................................................................................................................. 
B
 ............................................................................................................................................. 
C
 ............................................................................................................................................. 
D
 ............................................................................................................................................. 
(b)  (i)  Classify the type of reaction in each of A and D.
(2)
A
 ............................................................................................................................................. 
D
 ............................................................................................................................................. 
*(ii)  Reaction B can proceed via two possible reaction mechanisms, depending on the structure of the original compound. For each of the two isomers of C4H9Br shown below, draw the structure of the intermediate or transition state which is formed during the reaction. Explain in each case why the specified structure is more favourable.
(4)

Intermediate or transition state
Explanation
 ............................................................................................................................................. 
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 ............................................................................................................................................. 

Intermediate or transition state
Explanation
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(iii)  If C4H9I is used instead of C4H9Br in reaction D, the rate of formation of C4H9NH2 increases. Explain why the rate of reaction increases.
(1)
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 (c)  Halogenoalkanes are widely used as refrigerants and belong to the class of refrigerants that cool by change of state (typically by boiling).
(i)  Suggest how halogenoalkanes cool by change of state.
(1)
 ............................................................................................................................................. 
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 (ii)  Suggest two characteristics or properties desirable in a refrigerant.
(2)
1
 ............................................................................................................................................. 
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2
 ............................................................................................................................................. 

(Total for question = 14 marks)

Q16.
 The compound

has the systematic name
   A  2-chlorobutane
   B  3-chlorobutane
   C  1-chloro-1-methylpropanel
   D  1-chloro-2-methylbutane
(Total for question = 1 mark)

Unit 2 - Jun 2012
Q17.
These questions concern the use of infrared (IR) spectra to identify organic compounds. The IR absorption ranges associated with some organic functional groups are given below.
   A       O—H stretching in alcohols at 3750 − 3200 cm−1
   B       CO stretching in aldehydes at 1740 − 1720 cm−1
   C       CO stretching in ketones at 1700 − 1680 cm−1
   D       CO stretching in carboxylic acids at 1725 − 1700 cm−1

      (a) When propan−2−ol is refluxed with potassium dichromate(VI) and sulfuric acid, the product will show a peak due to
(1)
   A
   B
   C
   D

      (b) When propan−1−ol is heated with potassium dichromate(VI) and sulfuric acid, the product, that is distilled off as it is formed, will show a peak due to 
(1)
   A
   B
   C
   D
(Total for question = 2 marks)

Q18.
 The steps below show the reaction mechanism for the reaction of a halogenoalkane with sodium hydroxide in aqueous solution to form an alcohol.

(a) (i) Name X and Z.
(2)
X
 ............................................................................................................................................. 
Z
 ............................................................................................................................................. 
(ii) Draw the skeletal formula of X.
(1)

(iii) What type of alcohol is Z?.
(1)
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(b) (i) Name the mechanism and type of reaction shown above.
(2)
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(ii) Explain what the curly arrows shown in the mechanism represent.
(1)
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*(iii) Suggest the shape of the intermediate Y. Explain your answer.
(3)
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(iv) If the reaction is carried out in alcoholic (ethanolic) rather than aqueous solution, a different type of reaction occurs and a different product is formed. Name the type of reaction that occurs in alcoholic (ethanolic) solution and identify the product by name or formula.
(2)
Type of reaction
 ............................................................................................................................................. 
Product

(c) The alcohol Z (shown below) resists oxidation. However, Z has three structural isomers which are readily oxidized. On complete oxidation, one isomer forms a ketone and the other two isomers form carboxylic acids.

(i) Draw the structural formula of the isomer of Z that forms a ketone.
(1)
(ii) Draw the structural formulae of the isomers of Z that form carboxylic acids.
(2)

(Total for question = 15 marks)
Q19.
       Which of the following formulae does not represent 2,2−dimethylpropan−1−ol?
(Total for question = 1 mark)
Unit 2 - Jun 2013
Q20.

The systematic name of the compound with skeletal formula shown above is
   A    1,1-dimethylethanol.
   B    2,2-dimethylethanol.
   C    2-methylpropan-1-ol.
   D    2-methylpropan-2-ol.
(Total for Question = 1 mark)
Q21.
Which of the following could be used to oxidize ethanol to ethanoic acid?
   A    Concentrated H2SO4
   B    
   C    H+/Cr3+
   D    Concentrated NaOH solution
(Total for Question = 1 mark)
Q22.
The alcohol shown below can be classified as

   A    just primary.
   B    primary and secondary.
   C    just secondary.
   D    secondary and tertiary.

(Total for Question = 1 mark)
Q23.
(a)  The products of the reaction when 2-chlorobutane is heated with sodium hydroxide depend on the conditions.
(i)  What condition, other than a suitable temperature and sodium hydroxide concentration, would produce a mixture of but-1-ene and but-2-ene?
(1)
 ............................................................................................................................................. 

(ii)  What type of reaction occurs in (a)(i)?
(1)
 ............................................................................................................................................. 

(iii)  What condition, other than a suitable temperature and sodium hydroxide concentration, would produce butan-2-ol in the reaction of 2-chlorobutane with sodium hydroxide?
(1)
 ............................................................................................................................................. 

(iv)  Suggest the mechanism for the reaction of 2-chlorobutane with hydroxide ions to form butan-2-ol. Use curly arrows to show the movement of electron pairs.
(2)

(b)  Phosphorus(V) chloride, PCl5, can be used to test for the –OH group.

Describe what would be seen when phosphorus(V) chloride is added to butan-2-ol. Give the equation for the reaction. State symbols are not required.
(2)
Observation
 ............................................................................................................................................. 
Equation

(c)  A tertiary alcohol, A, is an isomer of butan-2-ol.
(i)  Butan-2-ol and A can be distinguished by warming separate samples with a mixture of potassium dichromate(VI) and sulfuric acid. State the observations which would be made with each alcohol.
(2)
Observation with butan-2-ol
 ............................................................................................................................................. 
Observation with A
 ............................................................................................................................................. 
(ii) Give the structural formula of the organic product which forms when butan-2-ol is oxidized.
(1)

(iii)  Explain how infrared spectroscopy could be used to detect whether butan-2-ol has been oxidized.
(1)
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 ............................................................................................................................................. 

(Total for Question = 11 marks)

Q24.
Ethane-1,2-diol, CH2OHCH2OH, is commonly used in antifreeze for cars to lower the freezing temperature of the water in the car radiator. It reacts in a similar way to ethanol but both of the alcohol groups can react.

(a)  Write an equation for the complete reaction between sodium and ethane-1,2-diol. State symbols are not required.
(2)

(b)  Ethane-1,2-diol is very quickly oxidized to ethanedioic acid, (COOH)2, even under the conditions shown below.

However, ethanol requires stronger oxidizing conditions to be converted into ethanoic acid.
Explain how you would change the above apparatus to achieve this oxidation of ethanol.
(2)
............................................................................................................................................. 
 ............................................................................................................................................. 
(c)  Draw the skeletal formula of ethanedioic acid.
(1)

(d)  Explain why phosphorus(V) chloride, PCl5, would not be a suitable reagent to be used to distinguish between ethane-1,2-diol and ethanedioic acid.
(1)
 ............................................................................................................................................. 
 (e)  (i)  Depending on the reaction conditions, ethanol can be oxidized to either an aldehyde or to carboxylic acid. Infrared spectroscopy is a suitable technique for determining whether the oxidation product obtained is an aldehyde or a carboxylic acid.
Draw, on the spectrum below, any peak(s) that you would expect to see between 4000 and 1500 cm−1 if the product was an aldehyde and not a carboxylic acid.
(2)
DATA
The IR absorption ranges associated with some organic functional groups are given below:
O—H stretching in alcohols (variable, broad) at 	3750 − 3200 cm−1 	
O—H stretching in carboxylic acids (weak) at 	3300 − 2500 cm−1 	
CO stretching in aldehydes (strong) at 	1740 − 1720 cm−1 	
CO stretching in ketones (strong) at 	1700 − 1680 cm−1 	
CO stretching in carboxylic acids, alkyl (strong) at 	1725 − 1700 cm−1 	
C—H stretching in aldehydes (weak) at 	2900 − 2820 cm−1 	
                                       and (weak) at 	2775 − 2700 cm−1 	
 
(ii)  The infrared spectrum of the distillate from the reaction in (e)(i) included a peak at 3750–3200 cm−1.

What substance is likely to have caused this?
(1)
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(iii)  Mass spectrometry can be used to identify the products of the oxidation of ethanol. Suggest the formula of a fragment that would show when ethanoic acid is produced and would not be present in either ethanol or ethanal.
(1)
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(f)  Treatment of 2-bromoethanol, CH2BrCH2OH, with aqueous sodium hydroxide would be one way to produce ethane-1,2-diol.

(i)  Complete a possible mechanism for this reaction in the space below.
(3)

(ii)  Classify the mechanism and type of reaction in (f)(i):
(2)
Mechanism
 ............................................................................................................................................. 
Type
 ............................................................................................................................................. 

(g)  Aqueous silver nitrate can be used to test for the presence of bromide ions. Write an ionic equation for the reaction. Include state symbols in your answer.
Ionic Equation

*(h)  It can be difficult to distinguish between the colours of the silver halides. The use of solutions of ammonia can be very helpful.

A silver halide dissolved in concentrated ammonia to form a colourless solution.

Explain why this result does not prove conclusively that the silver halide was silver bromide and give a further test to confirm that the silver halide is silver bromide.

(2)
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(Total for Question = 19 marks)

Q25.
The term "reflux" is best described as
   A    continuous evaporation and condensation.
   B    heating to evaporation and separation.
   C    heating under reduced pressure and separation.
   D    constant boiling.

(Total for Question = 1 mark)

Unit 2 - Jun 2014
Q26.
Hydrogen, H2, is not a completely 'carbon neutral' fuel. Which of the following is an incorrect reason for this?
   A    Some CO2 is released in the transportation of H2 fuel.
   B    CO2 is made when the electricity is generated for the manufacture of H2.
   C    A small amount of CO2 is produced on the combustion of H2 fuel.
   D    CO2 is released during the construction of the H2 manufacturing plant.

  
(Total for question = 1 mark)

Q27.
 Which of the following isomeric alcohols, with molecular formula C5H12O, can be oxidized to a carboxylic acid with five carbon atoms?

  
(Total for question = 1 mark)

Q28.
Insect-borne diseases, such as malaria, affect the lives of millions of people. Chemists are constantly finding new compounds to combat the transmission of these diseases. One such compound is the insect repellent commonly called p-menthane-3,8-diol (this is not its systematic name). It is used to protect both humans and animals.
The structure of p-menthane-3,8-diol is shown below.

p-menthane-3,8-diol is found naturally in the leaves of Eucalyptus citriodora, which is native to Australia and is commonly known as 'Lemon Bush'. It can be extracted from these leaves but is currently commercially prepared by chemical synthetic pathways. However, the commercially-made chemical has been found by some scientists to be less effective than the natural leaf extract.
It is possible that p-menthane-3,8-diol can kill microorganisms and it is this additional potential use and others which are being investigated by the chemical industry.
p-menthane-3,8-diol should not be confused with either methane or methanol.
(a)  p-menthane-3,8-diol has two alcohol functional groups. Classify the type of alcohol group on the far left of the structure drawn above and explain the meaning of the term 'functional group'.
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 
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(b)  Give the molecular formula of p-menthane-3,8-diol.
(1)
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(c)  p-menthane-3,8-diol is found in the oily extract from the leaves of the 'Lemon Bush'.
One method used to extract the oil is described below.
Initially, the leaves are ground up using a pestle and mortar with some sand and an organic solvent, such as cyclohexane.
(i)  Suggest why sand is used.
(1)
 ............................................................................................................................................. 
 ............................................................................................................................................. 

*(ii)  The solvent cyclohexane forms intermolecular forces with other organic molecules when they dissolve.
Identify these intermolecular forces and explain how they arise.
(3)
Type of intermolecular force
 ............................................................................................................................................. 
How they arise
............................................................................................................................................. 
 ............................................................................................................................................. 

(iii)  How could the sand and other solid residue be removed from the mixture?
(1)
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(iv)  At this stage, either anhydrous magnesium sulfate or calcium chloride is added. Suggest the reason for this.
(1)
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*(v)  A student suggested using the following apparatus to remove the cyclohexane from the mixture.

Explain, in terms of the processes that occur in the above apparatus, why this method is unsuitable to remove the cyclohexane.
Suggest how this apparatus could be adjusted for a successful separation.
DATA

·	Boiling temperatures: p-menthane-3,8-diol 266 °C; cyclohexane 81 °C(4)
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(d)  Spectroscopic techniques can be used to confirm the presence and identity of organic molecules such as p-menthane-3,8-diol.
(i)  Suggest how infrared spectroscopy could be used to confirm the presence of the functional group in a molecule such as p-menthane-3,8-diol.
(1)
 ............................................................................................................................................. 
 ............................................................................................................................................. 

(ii)  Suggest the identity of two fragment ions, with a m/e value of more than 13 but less than 20, that could be observed in a mass spectrum of p-menthane-3,8-diol.
(2)
First fragment ion
 ............................................................................................................................................. 
Second fragment ion
 ............................................................................................................................................. 

(e)  One reason why the synthetic p-menthane-3,8-diol may be less effective than the natural extract is because there are many isomers of this molecule.
Complete the structures below to show two structural isomers of p-menthane-3,8-diol which have the same number of alcohol functional groups and the same carbon skeleton.
(2)

*(f)  State two key principles of sustainability, and how the chemical industry might achieve these, when mass-producing a molecule such as p-menthane-3,8-diol.
(4)
Principle 1
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Principle 2
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(Total for question = 22 marks)
Q29.
Which of the following reagents gives a positive result with a tertiary alcohol?
   A    Acidified potassium dichromate(VI) solution
   B    Phosphorus(V) chloride
   C    Dilute sulfuric acid
   D    Bromine water

  
(Total for question = 1 mark)

Q30.
 This is a question about halogenoalkanes.
(a)  Halogenoalkanes can react with hydroxide ions in different ways depending on the conditions used. Using 1-chloro-1-fluoroethane, CH3CHClF, as an example of a halogenoalkane, the following reaction could occur in aqueous solution.
CH3CHClF + OH− → CH3CHOHF + Cl−
(i)  Suggest why it is unlikely that the fluorine atom in CH3CHClF would be substituted by the hydroxide ion.
(1)
 ............................................................................................................................................. 
 ............................................................................................................................................. 

*(ii)  A student attempted to draw the reaction mechanism for the reaction in (a)(i), but made a total of three errors.

Identify these errors and state how they should be corrected.
(3)
First error
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 ............................................................................................................................................. 
 ............................................................................................................................................. 

Second error
............................................................................................................................................. 
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Third error
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(iii)  In hot alcoholic solution, a different reaction may occur between halogenoalkanes and hydroxide ions.
Write the equation for the reaction between 1-chloro-1-fluoroethane, CH3CHClF, and hydroxide ions in alcoholic solution.
(2)

(b)  Chloroethane can be produced in various ways as shown below. Identify, by name or formula, the reagent needed for each of these reactions.
(3)

(c)  (i)  Chloroethane will react with alcoholic ammonia initially to produce ethylamine. Complete the equation for this reaction.
(1)
.............................. + NH3 → .............................. + ..............................

(ii)  Name the type and mechanism of the reaction occurring in (c)(i).
(2)
 ............................................................................................................................................. 
 ............................................................................................................................................. 

(iii)  What feature of the ammonia molecule enables the reaction in (c)(i) to take place?
(1)
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(iv)  If aqueous ammonia was used in (c)(i), instead of alcoholic ammonia, suggest the identity of the organic product that would be formed.
(1)
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(d)  Dichlorodifluoromethane, CCl2F2, is also known as Freon 12 and its manufacture was banned in 1994 under the terms of the Montreal Protocol.

(i)  Complete the equation for the initiation stage and suggest equations for two of the propagation stages and a termination stage for the mechanism of the reaction that this molecule might undergo with ozone.
(4)

Initiation           CCl2F2 →

Propagation 1

Propagation 2

Termination

*(ii)  Explain why the effect of Freon 12 molecules on the ozone layer was such a serious issue that scientists recommended its use to be discontinued.
(2)
 ............................................................................................................................................. 
............................................................................................................................................. 

(iii)  Freon 12, CCl2F2, could also be described as a "greenhouse gas". Explain what the term 'greenhouse gas' means.
(2)
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............................................................................................................................................. 

(iv)  Freon 12, and other similar molecules, are not normally viewed as contributors to the greenhouse effect. Suggest why this is so.
(1)
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(Total for question = 23 marks)