CAIE IGCSE Chemistry Organic Formulae and Homologous Series

Practise reading displayed structures, applying general formulae, identifying functional groups and naming members of organic homologous series.

Exam points

count atoms and bonds in displayed structures to obtain molecular formulae or complete a structure
apply the correct general formula to identify or construct a homologous-series member
identify functional groups and use them to classify and name the organic compound

Covered syllabus points

11.1.1—And interpret the displayed formula of 11.1.2—Write and interpret general formulae 11.1.3—Functional group as an atom or group 11.1.7—Structural formula is an unambiguous 11.1.8—Structural isomers as compounds with 11.1.4—Homologous series is a family of 11.1.5—Saturated compound has molecules in 11.1.6—An unsaturated compound has molecules 11.1.9—Homologous series features: same

[Maximum number: 2]

Fluorine is a Group VII element. Fluorine forms compounds with metals and non-metals.

(a)

Tetrafluoroethene is an unsaturated compound with the formula $\mathrm{C}_{2} \mathrm{~F}_{4}$ . Tetrafluoroethene is the monomer used to make the polymer poly(tetrafluoroethene).

[ 2 ]

(i)

What is meant by the term unsaturated?

[ 1 ]

(ii)

Draw the structure of a molecule of tetrafluoroethene. Show all of the atoms and all of the bonds.

[ 1 ]

[Maximum number: 2]

Propane, propene, propan-1-ol and propanoic acid are members of different homologous series. Molecules of these substances contain three carbon atoms.

(a)

Explain why members of a homologous series have similar chemical properties.

[ 1 ]

(b)

State the general formula of the homologous series to which propanoic acid belongs.

[ 1 ]

$\mathrm{C}_{\mathrm{n}} \mathrm{H}_{2 \mathrm{n}+1} \mathrm{COOH}$

[Maximum number: 7]

The names of four esters are listed.
> methyl propanoate ethyl propanoate propyl propanoate butyl propanoate

(a)

Esters are a family of organic compounds with similar chemical properties. They can be represented by the formula $\mathrm{C}_{n} \mathrm{H}_{2 n} \mathrm{O}_{2}$ .

[ 4 ]

(i)

State the name given to a family of organic compounds with similar chemical properties.

[ 1 ]

(ii)

Explain why members of a family of organic compounds have similar chemical properties.

[ 1 ]

(iii)

State the name given to a formula such as $\mathrm{C}_{n} \mathrm{H}_{2 n} \mathrm{O}_{2}$ .

[ 1 ]

(iv)

Determine the value of ' n ' in butyl propanoate.

[ 1 ]

(b)

Other esters, not in the list, have the same molecular formula as propyl propanoate, but different structures.

[ 3 ]

(i)

State the term used to describe substances with the same molecular formula but different structures.

[ 1 ]

(ii)

Name two esters with the same molecular formula as propyl propanoate.

1

2

[ 2 ]

All question bank results loaded

Covered syllabus points

11.1 Formulae, functional groups and terminology question 1

Question (a)

Question (i)

Question (ii)

11.1 Formulae, functional groups and terminology question 2

Question (a)

Question (b)

11.1 Formulae, functional groups and terminology question 3

Question (a)

Question (i)

Question (ii)

Question (iii)

Question (iv)

Question (b)

Question (i)

Question (ii)