International School of Johannesburg. Diploma Chemistry. Organic Chemistry (HL) Revision Questions. D. ( HNCH 2 CH 2 NHCOCH 2 NH ) (Total 1 mark)

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1 International School of Johannesburg Diploma Chemistry Organic Chemistry (HL) Revision Questions 1. The compounds H 2 NCH 2 CH 2 NH 2 and HOOCCH 2 COOH react to form a polymer. What is the structure of the repeating unit of the polymer? A. ( HNCH 2 CONHCH 2 CH 2 NHCO ) B. ( HNCH 2 CH 2 NHCOCH 2 CO ) C. ( OCCH 2 CONHCH 2 NHCO ) D. ( HNCH 2 CH 2 NHCOCH 2 NH ) 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 IB Questionbank Chemistry 1

2 3. What product is formed when CH 3 CH(OH)CH 3 is reacted with acidified potassium dichromate(vi)? A. CH 3 COOCH 3 B. CH 3 CH 2 CHO C. CH 3 CH 2 COOH D. CH 3 COCH 3 4. Benzene, C 6 H 6, is a planar compound which differs from the non-planar structure of cyclohexane, C 6 H 12. 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. (1) IB Questionbank Chemistry 2

3 (b) Explain why it is more common for benzene to undergo substitution reactions than addition reactions. (1) (Total 2 marks) 5. Halogenoalkanes can undergo S N 1 and S N 2 reactions with aqueous sodium hydroxide. Which halogenoalkane will react fastest with a 0.1 mol dm 3 solution of aqueous sodium hydroxide? A. 2-chloro-2-methylpropane B. 2-iodo-2-methylpropane C. 1-chlorobutane D. 1-iodobutane 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 S N 2 mechanism. C. Homolytic fission occurs between the carbon-bromine bond in bromoethane. D. The cyanide ion, :CN, acts as a nucleophile. IB Questionbank Chemistry 3

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 8. Propan-1-ol and propan-2-ol are two structural isomers of C 3 H 8 O. (i) State the equation for the complete combustion of C 3 H 8 O. (2) (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. IB Questionbank Chemistry 4

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. (5) (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. (2) (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. (2) IB Questionbank Chemistry 5

6 (iii) Other than polymerization, state one reaction of alkenes which is of economic importance. (1) (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 CH 2 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 11. Which structure could represent a repeating unit of a polymer formed from propene? A. ( CH 2 CH(CH 3 ) ) B. ( CH 2 CH 2 CH 2 ) C. ( CH(CH 3 ) CH(CH 3 ) ) D. ( CH 2 CH 2 ) IB Questionbank Chemistry 6

7 12. What is the correct order of reaction types in the following sequence? C 3 H 7 Br I C 3 H 7 OH II C 2 H 5 COOH III C 2 H 5 COOC 2 H 5 I II III A. substitution oxidation condensation B. addition substitution condensation C. oxidation substitution condensation D. substitution oxidation substitution 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 14. There are several structural isomers with the molecular formula C 5 H 11 Br. (a) Deduce the name of one of the isomers which can exist as enantiomers and draw three-dimensional representations of its two enantiomers. IB Questionbank Chemistry 7

8 (b) All the isomers react when warmed with a dilute aqueous solution of sodium hydroxide according to the equation below. C 5 H 11 Br + NaOH C 5 H 11 OH + NaBr (i) The reaction with 1-bromopentane proceeds by an S N 2 mechanism. Describe this mechanism using structural formulas and curly arrows to represent the movement of electron pairs. (ii) The reaction with 2-bromo-2-methylbutane proceeds by an S N 1 mechanism. Describe this mechanism using structural formulas and curly arrows to represent the movement of electron pairs. IB Questionbank Chemistry 8

9 (iii) Explain why 1-bromopentane reacts by an S N 2 mechanism whereas 2-bromo-2-methylbutane reacts by an S N 1 mechanism. (iv) Explain whether the boiling point of 1-bromopentane will be higher, lower or the same as that of 2-bromo-2-methylbutane. (v) The product C 5 H 11 OH 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. (2) IB Questionbank Chemistry 9

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. (4) (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. IB Questionbank Chemistry 10

11 (ii) Outline the economic importance of the reaction of diols with dicarboxylic acids. (1) (Total 4 marks) 16. Which is the correct classification of these alcohols? A. tertiary secondary primary B. tertiary primary secondary C. tertiary tertiary secondary D. secondary primary secondary 17. Which of the structures below is an aldehyde? A. CH 3 CH 2 CH 2 CH 2 OH B. CH 3 CH 2 COCH 3 C. CH 3 CH 2 COOCH 3 D. CH 3 CH 2 CH 2 CHO IB Questionbank Chemistry 11

12 18. Two compounds, A and D, each have the formula C 4 H 9 Cl. Compound A is reacted with dilute aqueous sodium hydroxide to produce compound B with a formula of C 4 H 10 O. Compound B is then oxidized with acidified potassium manganate(vii) to produce compound C with a formula of C 4 H 8 O. 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 C 4 H 10 O. 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 12

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 (Total 4 marks) chloro-3-methylbutane reacts with sodium hydroxide via an S N 2 mechanism. Explain the mechanism by using curly arrows to represent the movement of electron pairs. (Total 4 marks) IB Questionbank Chemistry 13