A Level Official Exam Material
FREE Past Paper Questions by Topic
If you need the markscheme, including the examiners' reports for each question, and more exam and teaching materials on this topic, contact me through the contact page
Unit 2: Energetics, Group Chemistry,
Halogenoalkanes and Alcohols
Halogenoalkanes and Alcohols
Topic 10: Organic Chemistry:
Halogenoalkanes, Alcohols and Spectra
For AS and A Level students
Q1. Answer the question with a cross in the box you think is correct .
If you change your mind about an answer, put a line through the box and then mark your new answer with a cross .
The structure of ethylamine is shown.
What type of reagent will attack the Cδ+ atom?
A electrophile
B free radical
C nucleophile
D oxidising agent
Use this space for any rough working.
Anything you write in this space will gain no credit.
(Total for question = 1 mark)
Q2. Answer the question with a cross in the box you think is correct .
If you change your mind about an answer, put a line through the box and then mark your new answer with a cross .
What is the structure of 2-bromo-3-chloro-2-methylbutane?
Q3. A chloroalkane is heated with dilute aqueous sodium hydroxide and the pure organic product is obtained.
When the organic product is warmed with acidified potassium dichromate(VI) solution, there is no change in colour.
The chloroalkane could be (1)
A 1-chlorobutane
B 2-chloro-2-methylpropane
C 1-chloro-2-methylpropane
D 2-chlorobutane
(Total for question = 1 mark)
Q4. Answer the questions with a cross in the boxes you think are correct .
If you change your mind about an answer, put a line through the box and then mark your new answer with a cross .
Separate samples of some halogenoalkanes were dissolved in ethanol and a few drops of silver nitrate solution added.
The faster the reaction of the halogenoalkane, the quicker a precipitate forms.
(a) Which of these halogenoalkanes reacts the fastest? (1)
A CH3CHICH3
B CH3CHBrCH3
C CH3CHClCH3
D CH3CHFCH3
(b) Which of these halogenoalkanes reacts the fastest? (1)
A CH3CHBrCH(CH3)CH3
B CH3CH2CBr(CH3)CH3
C CH3CH(CH2Br)CH2CH3
D CH3CH2CH2CH2CH2Br
(Total for question = 2 marks)
Q5. Which compound is hydrolysed most rapidly? (1)
A 1-chloropropane
B 1-chlorobutane
C 2-chloro-2-methylpropane
D 2-chlorobutane
(Total for question = 1 mark)
Q6. 1-bromobutane reacts with alkali:
CH3-CH2-CH2-CH2Br + OH− → CH3-CH2-CH2-CH2OH + Br−
The mechanism and type of reaction is: (1)
A electrophilic addition
B electrophilic substitution
C nucleophilic addition
D nucleophilic substitution
(Total for question = 1 mark)
Q7. Answer the question with a cross in the box you think is correct .
If you change your mind about an answer, put a line through the box and then mark your new answer with a cross .
Which structure represents a primary halogenoalkane?
Q8. Halogenoalkanes are useful reagents in organic synthesis.
Some reactions of 1-bromopropane are shown.
(b) Give the IUPAC name of the product of Reaction 3. (1) .............................................................................................................................................
(c) Complete the mechanism for Reaction 2.
Show the formation of the intermediate F and of the product.
Include curly arrows, and any relevant lone pairs and dipoles. (3)
*(d) The relative rates of hydrolysis of a series of halogenoalkanes were determined using the following method:
• five test tubes, each containing 2 cm3 of ethanol and 2 cm3 of aqueous silver nitrate, were placed in a water bath at 50 °C
• four drops of a different halogenoalkane were added to each test tube
• the time taken for a precipitate to appear in each test tube was recorded.
The results are shown.
Explain these results by considering:
• the chemical reaction occurring
• the structures of the halogenoalkanes
• the strengths of the carbon-halogen bonds. (6) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(Total for question = 14 marks)
Q9. This question is about some halogenoalkanes.
(a) Give the classification of each halogenoalkane shown in the table as primary, secondary or tertiary. (1)
(b) Samples of 1-iodobutane and 2-chloro-2-methylpropane were hydrolysed using aqueous silver nitrate in ethanol.
Explain whether or not it is possible to predict the relative rate of hydrolysis of these two compounds. (3) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(c) Butylamine is formed when 1-bromobutane reacts with excess concentrated alcoholic ammonia.
CH3CH2CH2CH2Br + 2NH3 → CH3CH2CH2CH2NH2 + NH4Br
(i) Give a reason why this reaction should be carried out by heating the reactants in a sealed tube rather than heating under reflux. (1)
............................................................................................................................................. .............................................................................................................................................
(ii) Complete the mechanism for this reaction by adding curly arrows, and any relevant lone pairs and dipoles. (4)
(d) Bromoethane is prepared by reacting ethanol with potassium bromide and concentrated sulfuric acid.
C2H5OH + KBr + H2SO4 → C2H5Br + KHSO4 + H2O
Calculate the maximum mass of bromoethane that could be prepared from 4.65 g of ethanol, 14.90 g of potassium bromide and a solution containing 16.35 g of H2SO4.
[Ar values: H = 1.0 C = 12.0 O = 16.0 S = 32.1 K = 39.1 Br = 79.9] (3)
*(e) The reaction between 2-bromopropane and potassium hydroxide takes place under two different conditions:
• in aqueous solution
• in ethanolic solution.
Compare and contrast these two reactions.
Include equations for the reactions.
Detailed mechanisms of these reactions are not required. (6) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(Total for question = 18 marks)
Q10. C2H5Br + NaOH → C2H4 + NaBr + H2O
This reaction is an example of
A addition.
B elimination.
C hydrolysis.
D oxidation.
(Total for Question = 1 mark)
Q11. The reaction of 1-chloropropane with water containing dissolved silver nitrate in the presence of ethanol is
A a redox reaction.
B a nucleophilic substitution.
C an electrophilic substitution.
D a free radical substitution.
(Total for Question = 1 mark)
Q12. Ethene reacts with bromine in the dark.
(i) What is the classification of the mechanism for the reaction between ethene and bromine? (1)
A electrophilic addition
B electrophilic substitution
C nucleophilic addition
D nucleophilic substitution
Q13. Ethene reacts with bromine in the dark.
(i) What is the classification of the mechanism for the reaction between ethene and bromine? (1)
A electrophilic addition
B electrophilic substitution
C nucleophilic addition
D nucleophilic substitution
Q14. The reaction of the halogenoalkane, C2H5Cl, with alcoholic ammonia is
A nucleophilic substitution.
B electrophilic substitution.
C reduction.
D elimination.
(Total for question = 1 mark)
Q15. 1-bromobutane is classified as a primary halogenoalkane and is one of the four structural isomers with a molecular formula C4H9Br.
Give the skeletal formula of the three isomers, other than 1-bromobutane, classifying the halogenoalkane in each case. (3)
Q16. Samples of 1-chloropropane and 1-bromopropane are warmed with water containing dissolved silver nitrate in the presence of ethanol.
The 1-chloropropane reacts more slowly because
A the C—Cl bond is more polar than the C—Br bond.
B the C—Cl bond is stronger than the C—Br bond.
C 1-chloropropane is less soluble than 1-bromopropane.
D 1-chloropropane is a weaker oxidizing agent than 1-bromopropane.
(Total for Question = 1 mark)
Q17. Equal amounts of 1–chlorobutane and 1–iodobutane are warmed with aqueous silver nitrate in the presence of ethanol. Why does 1–chlorobutane react more slowly?
A The C—Cl bond is more polar than the C—I bond.
B The C—Cl bond is stronger than the C—I bond.
C The C—I bond is more polar than the C—Cl bond.
D The C—I bond is stronger than the C—Cl bond.
(Total for question = 1 mark)
Q18. What is observed when a mixture of bromoethane and aqueous silver nitrate is warmed?
A Brown solution
B Cream precipitate
C Decolorisation
D Silver precipitate
(Total for question = 1 mark)
Q19. One method of preparing 1-bromobutane from butan-1-ol is given below. Procedure
You will need the following data to answer the questions.
(a) The use of the beaker of cold water in Step 1, and the slow addition of concentrated sulfuric acid in Step 2, both prevent a reaction which gives unwanted inorganic products.
Identify one of these unwanted products. State the type of reaction occurring when these products form. (2)
Product .............................................................................................................................................
Type of reaction ............................................................................................................................................. ............................................................................................................................................. (b)
(i) Explain why the condenser is set up so that the water flows from bottom to top, as shown in the diagram. (1) ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(ii) Without the reflux condenser, the procedure in Step 2 would become more hazardous. Explain why. (1) ............................................................................................................................................. .............................................................................................................................................
(c) To achieve the best possible yield of 1-bromobutane, the purification stages should involve the minimum number of transfers of the organic product from one piece of apparatus to another.
(i) How could the water layer be removed from the small beaker in Step 5 without transferring the organic product? (1) .............................................................................................................................................
(ii) Name the apparatus you would use to carry out the washing of the crude 1-bromobutane in Step 6.
Describe how you would obtain the organic layer from this mixture. (2) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(d) What is the purpose of Step 7? (1) ............................................................................................................................................. .............................................................................................................................................
(e) After Step 7, the crude 1-bromobutane is washed with pure water and separated again.
Two further steps are needed to obtain a pure sample of 1-bromobutane.
State what these steps are.
Detailed experimental procedures are not required, but you should name any reagents which are needed. (3)
Step 8 ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
Step 9 ............................................................................................................................................. ............................................................................................................................................. (f)
(i) Calculate the mass of butan-1-ol used in Step 1. (1)
(ii) In this experiment, a student obtained 7.5 g of 1-bromobutane.
Calculate the percentage yield of 1-bromobutane.
Assume that each mole of butan-1-ol can produce a maximum of one mole of 1-bromobutane.
Give your answer to two significant figures. (3)
(Total for question = 15 marks)
Q4. Which is a tertiary halogenoalkane?
A CHBr3
B (CH2Br)3CH
C (CH3)3CBr
D BrCH2C(CH3)3
(Total for question = 1 mark)
Q19. Grass is similar to many other plants in naturally releasing mixtures of volatile organic compounds.
Freshly-cut grass has a characteristic aroma because of the increased release of these compounds, which are known as green leaf volatiles (GLVs).
The most important contributors to this aroma are alcohols and aldehydes containing six carbon atoms.
The main compound giving freshly-cut grass its smell is Z-hex-3-enal.
The human nose can detect Z-hex-3-enal at levels as low as 1.0 ng dm−3 or 1.0 × 10−9 g dm−3 .
However, this compound is relatively unstable and rearranges to form the E isomer.
Some other GLVs are methanol, ethanol, Z-hex-3-en-1-ol and E-hex-2-enal.
It has been suggested that the release of these GLVs is part of a defence response by the plant.
In one study of plants attacked by caterpillars, the chemical composition of the GLVs changed to attract the natural insect predators of these caterpillars.
(a) Give the molecular formula of Z-hex-3-enal. (1) .............................................................................................................................................
(b) Draw the skeletal formula of the E-isomer of hex-3-enal. (1)
(c) An average nasal cavity has a volume of 30 cm3 .
Calculate the minimum number of molecules of Z-hex-3-enal that could be detected in this volume.
Data: Avogadro constant = 6.02 × 1023 mol–1 Molar mass of Z-hex-3-enal = 98 g mol–1 (2)
(d) Complete the table with saturated, straight-chain alcohols having six carbon atoms that could be GLVs by giving one example in each case. (4)
(e) The compound 2-chloro-2-methylpentane has six carbon atoms.
(i) It can be converted into a tertiary alcohol with aqueous sodium hydroxide.
Complete the equation for this reaction. (1)
(ii) What class of reagent is the hydroxide ion in this reaction? (1) .............................................................................................................................................
(iii) In different conditions, 2-chloro-2-methylpentane undergoes an elimination reaction that produces an alkene.
Complete the reaction mechanism with the appropriate curly arrow.
State the essential condition for this reaction. (4)
Essential condition for reaction .............................................................................................................................................
(f) Methanol and ethanol are both GLVs.
There are a number of fragment peaks which appear in the mass spectra of both compounds but, somewhat surprisingly, the OH+ peak at m / e = 17 is not one of them.
(i) Suggest the formulae and m / e values of two fragment ions that you would expect to occur in both spectra. (2)
First fragment ion ....................................................................................
Second fragment ion ................................................................................
(ii) Give the formula of one fragment ion that you would expect to be present in the mass spectrum of ethanol but absent from that of methanol. (1)
*(g) Z-hex-3-en-1-ol is only sparingly soluble in water but completely miscible with ethanol.
By reference to intermolecular forces, fully explain this difference in solubility.
Detailed explanations of the forces involved are not required. (4) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................
(Total for question = 21 marks)
Q20. Answer the question with a cross in the box you think is correct .
If you change your mind about an answer, put a line through the box and then mark your new answer with a cross .
Which could be the infrared spectrum of CH2=CHCH2OH?
Q21. Answer the question with a cross in the box you think is correct .
If you change your mind about an answer, put a line through the box and then mark your new answer with a cross .
The infrared spectrum of an organic compound is shown.
Which of these compounds would give this infrared spectrum? (1)
A hexanal
B hexane
C hexanoic acid
D hexan-1-ol
(Total for question = 1 mark)
Q22. Answer the question with a cross in the box you think is correct .
If you change your mind about an answer, put a line through the box and then mark your new answer with a cross .
In a mass spectrum, the molecular ion is the ion which always has the
A greatest abundance
B greatest stability
C highest charge
D highest mass/charge ratio
(Total for question = 1 mark)
Q23. Butan-1-ol and butan-2-ol are isomers.
Which m/z value would be expected to have a significant peak in the mass spectrum of butan-1-ol but not that of butan-2-ol? A 15
B 29
C 43
D 57
(Total for question = 1 mark)
Q24. A sample of 1,2-dichloroethane, CH2ClCH2Cl, contains only the isotopes 1H, 12C, 35Cl and 37Cl.
How many molecular ion peaks are there in its mass spectrum? (1)
A 1
B 2
C 3
D 4
(Total for question = 1 mark)
Q25. Answer the question with a cross in the box you think is correct .
If you change your mind about an answer, put a line through the box and then mark your new answer with a cross .
The mass spectrum of propanone is shown.
Which fragment is most likely to produce the peak at m / z = 43?
A CH3CH2CH2 +
B CH3CO+
C CH2CHO+
D CHCH2O+
(Total for question = 1 mark)
If you need the markscheme, including the examiners' reports for each question, and more exam and teaching materials on this topic, contact me through the contact page