A LevelChemistryCIETopic Questions13. An Introduction to AS Level Organic Chemistry13.1 Formulas, Functional Groups & the Naming of Organic Compounds

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First teaching 2023

First exams 2025

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Formulas, Functional Groups & the Naming of Organic Compounds (CIE A Level Chemistry)

Topic Questions

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1a
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This question is about organic compounds found in living organisms.

Terpenes are a class of organic compounds widely used as fragrances in products such as perfumes. For example, one of the simpler terpenes, nerol is found in many essential oils such as lemongrass and hops. The structure of nerol is shown in Fig 1.1.

 
4-1_q1a-h-ocr-a-as--a-level-hard-sq
 
Fig 1.1
 
i)
State the molecular formula of nerol and calculate the relative molecular mass of nerol. 
 
[2]
 
ii)
Draw the displayed formula of nerol.
 
[1]

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1b3 marks

Explain whether nerol shows geometrical (cis-trans) and optical isomerism. In your answer, identify any relevant points in the structure of nerol.

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1c2 marks

Two structural isomers of nerol are linalool and geraniol. They are unsaturated alcohols with similar chemical properties that are both used in perfumes. 

 

The IUPAC names for both linalool and geraniol are shown in Table 1.1.

 
Table 1.1
 

Isomer

IUPAC name

Linalool

3,7-dimethylocta-1,6-dien-3-ol

Geraniol

3,7-dimethylocta-2,6-dien-1-ol
  

Draw the skeletal formulae for these two isomeric alcohols.

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1a2 marks

X, Y and Z are all organic compounds.

X can be manufactured by the oxidation of propene.

CH3CHCH2 + O2 → CH2CHCHO + H2O

Name X and state the functional groups that are present.

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1b2 marks

Fig. 1.1 shows the skeletal formula of Y.

isobutyric-acid

Fig. 1.1

State the empirical and molecular formulae of Y.

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1c1 mark

Z is a saturated hydrocarbon that is an isomer of pentene. The molecular formula of Z matches the general formula of the homologous series of alkenes.

Draw the skeletal formula of Z.

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2a1 mark

Crotonic acid, C4H6O2, is used in the manufacture of paints and adhesives.

State the empirical formula of crotonic acid.

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2b2 marks

The systematic name of crotonic acid is but-2-enoic acid.

Draw two displayed formulae for possible isomers of crotonic acid that retain the carboxylic acid functional group.

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2c5 marks

Oleic acid is a fatty acid which occurs naturally in different animals and plants. The structure of oleic acid is shown in Fig. 2.1.

1-6

Fig. 2.1

i)
Identify the type of formula shown in Fig. 2.1.
 
[1]
ii)
Deduce the molecular formula of oleic acid.
 
[1]
iii)
Explain whether oleic acid belongs to the same homologous series as crotonic acid.
[3]

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3a4 marks

A selection of chemical compounds is analysed. The displayed formulae of these compounds are shown in Table 3.1.

Table 3.1

Compound  Structural formula Functional group(s) present
1 8j2tvQXQ_3-bromo-2-methylpropan-1-ol  
2 2-chloropropanal-1  
3 2-chloro-but-2-en-1-ol-1  
4 bMhaTdU-_3-methyl-but-2-enoic-acid  

Complete Table 3.1 to identify the functional groups present in compounds 1 - 4.

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3b4 marks

Name compounds 1 - 4.

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3c2 marks

Identify which compounds have an empirical formula that is the same as their molecular formula. Explain your answer.

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