AQA A Level Chemistry

Topic Questions

7.4 Aromatic Chemistry (A-level only)

11 mark

What are the reagents required for the conversion of benzene to nitrobenzene?

  • Hydrogen gas in presence of nickel catalyst

  • Concentrated nitric acid and concentrated hydrochloric acid

  • Concentrated sulfuric acid and concentrated nitric acid

  • Tin with concentrated hydrochloric acid

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21 mark

Cyclohexene is an unsaturated hydrocarbon and can undergo hydrogenation as shown 

7-4-e-q2-aqa-al-chemistry-mcq

The expected value for the enthalpy value for the hydrogenation of benzene is
-360 kJ mol-1. The actual value for the reaction is -208 kJ mol-1.

Which is the correct explanation? 

  • The s orbitals overlap to produce a stable structure

  • The bond length of the C=C bonds are shorter than the C-C bonds

  • Delocalisation of electrons in the benzene ring increases the stability

  • Each carbon in benzene has three covalent bonds

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31 mark

The correct equation for the generation of an electrophile formed in Friedel-Crafts alkylation is

  • CH3CH2Cl + AlCl3 → CH3CH2+ + AlCl4- 

  • HNO3 + 2H2SO4  → NO2+ + 2HSO4- + H3O+

  • AlCl 4- + H+  → AlCl 3 + HCl 

  • CH3COCl + AlCl3 → CH3CO+ + AlCl4- 

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41 mark

Which part of the following mechanism is not correct?7-4-e-q4-aqa-al-chemistry-mcq

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51 mark

Which product is formed when benzene, C6H6, reacts with ethanoyl chloride, CH3COCl, in the presence of aluminium chloride, AlCl3?

  • C6H6COCH3

  • HCl

  • C6H5CH3CO

  • C6H5CH2CH3

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11 mark

Which statement correctly explains the difference between the enthalpy change for the hydrogenation of cyclohexa-1,4-diene and the hydrogenation of cyclohexa-1,3-diene?

  • Cyclohexa-1,4-diene is less stable than cyclohexa-1,3-diene

  • Cyclohexa-1,4-diene is more stable than cyclohexa-1,3-diene

  • There is greater overlap of pi bonds in cyclohexa-1,4-diene

  • The C=C double bonds are closer together cyclohexa-1,3-diene which creates repulsion

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21 mark

Propene reacts with benzene in the presence of aluminium chloride and hydrogen chloride.

What are the most likely products of this reaction?

 

  • C6H5CH2CH2CH3, AlCl3 and HCl 

  • C6H5CH(CH3)2, AlCl3 and HCl 

  • C6H5COCH2CH3, AlCl3 

  • C6H5CH2CH3, AlCl3 and HCl 

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31 mark

Which statement about the reactions of benzene is correct?

  • Ammonia is not a strong enough nucleophile to undergo nucleophilic substitution with benzene 

  • During electrophilic substitution, the electrophile attacks the delocalised electrons in the benzene ring 

  • Addition reactions do not require delocalised electrons to form new bonds

  • The delocalised system in benzene will repel attack from a nucleophile 

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41 mark

Which product(s) are formed when the theoretical compound cyclohexa-1,3,5-triene reacts with one molecule of bromine?

7-4-h-q4-aqa-al-chemistry-mcq

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51 mark

Compound B, C8O3H7N, is formed in two steps from benzene. What are the possible steps for the formation of compound B.

 

 

Step 1

Step 2

  A    

AlCl3 and CH3COCl

Conc HNO3 and H2SO4

B

Conc HNO3 and H2SO4

AlCl3, HCl, and C2H4

C

Conc HNO3 and H2SO4

Sn, conc HCl and NaOH

D

AlCl3 and CH3COCl

Sn, conc HCl and NaOH

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11 mark

Benzene can undergo nitration to form nitrobenzene. Which of the following statements is not correct?

  • Concentrated nitric acid acts as a base

  • A nitronium ion acts as an electrophile

  • HSO4- is produced in the formation of the electrophile

  • Aluminum chloride is required as a catalyst for the reaction

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21 mark

Which of the following reagents would be suitable for the reduction of nitrobenzene to produce phenylamine?

  • LiAlH4 in dry ether

  • NaBH4

  • Fe in presence of HCl

  • H2 in presence Mg catalyst

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31 mark

A student reacted 2.5 g of methylbenzene, C6H5CH3, with one mole of bromine, Br2, in the presence of aluminium bromide, AlBr3

The mass of the organic product formed is

  • 6.8 g

  • 2.2 g

  • 4.6 g

  • 4.7 g

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41 mark

Which of the following is correct?

       

Bond angles present in cyclohexene

A

109.5 o only

B

109.5 o and 120 o

C

120 o only

D

109.5 o and 107 o



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51 mark

Which of the following explains why the enthalpy of hydrogenation of benzene is lower than expected?

  • The overlap of p-orbitals allows electrons to become delocalised

  • Benzene contains both single and double bonds

  • The carbon-carbon bond lengths in benzene are shorter than a carbon-carbon single bond

  • Benzene contains sp2 hybridised carbon atoms

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