IB Questionbank Chemistry 1

International School of Johannesburg

Diploma Chemistry

Organic Chemistry (HL) Revision Questions

1. The compounds H2NCH2CH2NH2 and HOOCCH2COOH react to form a polymer. What is the structure of the repeating unit of the polymer?

A. ( HNCH2CONHCH2CH2NHCO )

B. ( HNCH2CH2NHCOCH2CO )

C. ( OCCH2CONHCH2NHCO )

D. ( HNCH2CH2NHCOCH2NH ) (Total 1 mark)

2. Which two molecules are cis-trans isomers of each other?

A. X and Z

B. X and Y

C. W and Y

D. W and Z (Total 1 mark)

IB Questionbank Chemistry 2

3. What product is formed when CH3CH(OH)CH3 is reacted with acidified potassium dichromate(VI)?

A. CH3COOCH3

B. CH3CH2CHO

C. CH3CH2COOH

D. CH3COCH3 (Total 1 mark)

4. Benzene, C6H6, is a planar compound which differs from the non-planar structure of cyclohexane, C6H12. The structures of benzene and the most stable form of cyclohexane are represented below.

(a) With reference to the compounds benzene, cyclohexane and 1,3-cyclohexadiene, state which compound would contain the shortest carbon-carbon bond length.

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IB Questionbank Chemistry 3

(b) Explain why it is more common for benzene to undergo substitution reactions than addition reactions.

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(Total 2 marks)

5. Halogenoalkanes can undergo SN1 and SN2 reactions with aqueous sodium hydroxide. Which halogenoalkane will react fastest with a 0.1 mol dm3 solution of aqueous sodium hydroxide?

A. 2-chloro-2-methylpropane

B. 2-iodo-2-methylpropane

C. 1-chlorobutane

D. 1-iodobutane (Total 1 mark)

6. Propanitrile can be prepared by reacting bromoethane with potassium cyanide. Which statement is not correct about the reaction between bromoethane and potassium cyanide?

A. The reaction is bi-molecular.

B. The reaction follows the SN2 mechanism.

C. Homolytic fission occurs between the carbon-bromine bond in bromoethane.

D. The cyanide ion, :CN, acts as a nucleophile. (Total 1 mark)

IB Questionbank Chemistry 4

7. Which organic molecule is not a structural isomer of pentan-1-ol?

A. pentan-2-ol

B. 2-methylpentan-2-ol

C. 2-methylbutan-2-ol

D. pentan-3-ol (Total 1 mark)

8. Propan-1-ol and propan-2-ol are two structural isomers of C3H8O.

(i) State the equation for the complete combustion of C3H8O.

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(ii) Both propan-1-ol and propan-2-ol can be oxidized in aqueous solution by potassium dichromate(VI). State any necessary conditions for the oxidation to occur and describe the colour change during the oxidation process.

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IB Questionbank Chemistry 5

(iii) State the name(s) and structure(s) of the organic product(s) that can be formed when each of the alcohols is oxidized and suggest why one of the alcohols gives two organic products and the other only gives one organic product.

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(Total 10 marks)

9. (i) Describe a chemical test that could be used to distinguish between propane and propene. In each case state the result of the test.

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(ii) Under certain conditions propene can polymerize to form poly(propene). State the type of polymerization taking place and draw a section of the polymer to represent the repeating unit.

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IB Questionbank Chemistry 6

(iii) Other than polymerization, state one reaction of alkenes which is of economic importance.

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(Total 5 marks)

10. Which is the best definition of structural isomers?

A. Compounds which have atoms with the same atomic numbers but different mass numbers

B. Compounds which have the same general formula but differ by a CH2 group

C. Compounds which have the same empirical formula but different molecular formulas

D. Compounds which have the same molecular formula but different arrangements of atoms (Total 1 mark)

11. Which structure could represent a repeating unit of a polymer formed from propene?

A. ( CH2CH(CH3) )

B. ( CH2CH2CH2 )

C. ( CH(CH3)CH(CH3) )

D. ( CH2CH2 ) (Total 1 mark)

IB Questionbank Chemistry 7

12. What is the correct order of reaction types in the following sequence?

C3H7Br oI C3H7OH oII C2H5COOH oIII C2H5COOC2H5

I II III

A. substitution oxidation condensation

B. addition substitution condensation

C. oxidation substitution condensation

D. substitution oxidation substitution (Total 1 mark)

13. Which substances are possible products of the incomplete combustion of octane?

A. Carbon dioxide and hydrogen gas

B. Carbon monoxide and water vapour

C. Carbon monoxide and hydrogen gas

D. Methane and hydrogen gas (Total 1 mark)

14. There are several structural isomers with the molecular formula C5H11Br.

(a) Deduce the name of one of the isomers which can exist as enantiomers and draw three-dimensional representations of its two enantiomers.

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(3)

IB Questionbank Chemistry 8

(b) All the isomers react when warmed with a dilute aqueous solution of sodium hydroxide according to the equation below.

C5H11Br + NaOH C5H11OH + NaBr

(i) The reaction with 1-bromopentane proceeds by an SN2 mechanism. Describe this mechanism using structural formulas and curly arrows to represent the movement of electron pairs.

(3)

(ii) The reaction with 2-bromo-2-methylbutane proceeds by an SN1 mechanism. Describe this mechanism using structural formulas and curly arrows to represent the movement of electron pairs.

(3)

IB Questionbank Chemistry 9

(iii) Explain why 1-bromopentane reacts by an SN2 mechanism whereas 2-bromo-2-methylbutane reacts by an SN1 mechanism.

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(iv) Explain whether the boiling point of 1-bromopentane will be higher, lower or the same as that of 2-bromo-2-methylbutane.

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(v) The product C5H11OH formed from the reaction with 1-bromopentane is warmed with ethanoic acid in the presence of a few drops of concentrated sulfuric acid. State the name of the type of reaction taking place and the structural formula of the organic product.

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IB Questionbank Chemistry 10

(c) If the conditions of the reaction in (b) are changed so that a hot solution of sodium hydroxide in ethanol is used then a different reaction occurs. The reaction with 2-bromo-2-methylbutane gives two different organic products. State the type of reaction taking place and suggest the identity (name or structure) of these two products. Explain whether or not they can exist as geometrical isomers.

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(Total 21 marks)

15. Dihalogenoalkanes can react with warm dilute potassium hydroxide solution to form diols. These diols can react with dicarboxylic acids.

(i) Deduce the equation for the reaction of benzene-1,4-dicarboxylic acid with the diol formed from 1,5-dibromopentane.

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IB Questionbank Chemistry 11

(ii) Outline the economic importance of the reaction of diols with dicarboxylic acids.

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(Total 4 marks)

16. Which is the correct classification of these alcohols?

1 2 3

1 2 3

A. tertiary secondary primary

B. tertiary primary secondary

C. tertiary tertiary secondary

D. secondary primary secondary (Total 1 mark)

17. Which of the structures below is an aldehyde?

A. CH3CH2CH2CH2OH

B. CH3CH2COCH3

C. CH3CH2COOCH3

D. CH3CH2CH2CHO (Total 1 mark)

IB Questionbank Chemistry 12

18. Two compounds, A and D, each have the formula C4H9Cl.

Compound A is reacted with dilute aqueous sodium hydroxide to produce compound B with a formula of C4H10O. Compound B is then oxidized with acidified potassium manganate(VII) to produce compound C with a formula of C4H8O. Compound C resists further oxidation by acidified potassium manganate(VII).

Compound D is reacted with dilute aqueous sodium hydroxide to produce compound E with a formula of C4H10O. Compound E does not react with acidified potassium manganate(VII).

Deduce the structural formulas for compounds A, B, C, D and E.

A:

B:

C:

D:

E:

(Total 5 marks)

IB Questionbank Chemistry 13

19. Deduce an equation for the reaction between propanoic acid and methanol. Identify the catalyst and state the name of the organic compound, X, formed.

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20. 2-chloro-3-methylbutane reacts with sodium hydroxide via an SN2 mechanism.

Explain the mechanism by using curly arrows to represent the movement of electron pairs.

(Total 4 marks)