Chemistry, Third edition

328 17 · ORGANIC CHEMISTRY: HYDROCARBONS

17.1.Write the formula of n-hexane in three different ways.

17.2.Write the structural formulae of the five isomers of

hexane and name them.

17.3.Name the following compounds:

(i)CH 3 CH=CHCH 2 CH 3

H 3 CCH 3

(ii) C=CHCH 2 CH

H 3 CCH 3

17.4.Write structural formulae for:

(i) pent-1-ene

(ii)5-chlorohex-2-ene

(iii)4,4-dimethylpent-2-ene

(iv)buta-1,3-diene

(v)methylcyclopentane

(vi)5-methyloct-3-yne.

17.5.Which of the following can exist as geometric isomers

(cisandtransforms)?

(i) (CH 3 ) 2 C=CH 2

(ii)CH 3 CH=CHCH 3

(iii)CH 3 CH=CHCH 2 CH 3.

17.6.Write the structural formulae of, and name, the follow-

ing compounds:

(i) The product of the reaction of pent-1-ene with bromine

water.

(ii)The product of the reaction of but-1-ene with alkaline

potassium permanganate solution.

(iii)The product of the reaction of trans-but-2-ene with

hydrogen.

17.7.Give the structural formulae of:

(i) trans-1,2-dibromoethene

(ii)trans-1-chloroprop-1-ene

(iii)cis-hex-3-ene.

17.8.Write the structure of tetrafluoroethene. This alkene

polymerizes to form polytetrafluoroethene (PTFE). Write the

equation for the reaction. See if you can find what PTFE is used

for in the home.

17.9.A compound is composed of 88.9% C and 11.1% H by

mass.

(i) What is the empirical formula of the compound?

(ii)If the molecular mass of the compound is 54 u, what is the

molecular formula of the compound?

(iii)Draw the structure of, and name, all possible isomers of

the compound.

17.10.Benzopyrene, C 20 H 12 , is a fused ring aromatic com-

pound. Write its structural formula.

17.11.Use the average bond enthalpies listed in Table 13.4 to

calculate the standard enthalpy of formation of benzene –

assume that the atoms are arranged according to the Kekulé

structure

You are given the additional information (at 298K)

C 6 H 6 (l)C 6 H 6 (g) H^ —= 31 kJ mol^1

C(s)C(g) H—^ = 717 kJ mol^1

and the enthalpy diagram

Compare your calculated value for the standard enthalpy of

formation of benzene with the experimental value of

50 kJ mol^1. Why is your value different?

Revision questions

6C(s) + 3H 2 (g)

C 6 H 6 (g)

C 6 H 6 (l)

Progress of reaction

ΔH 3

ΔH 2

ΔH 1

ΔH 4

6C(g) + 3H 2 (g)

Enthalpy

H 2 —^

H 4 —^

H 1 —^

H 3 —^

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