A quick introductory look at the alcohols

4 marks · Normal

Alcohols form a homologous series. The structure and naming of these compounds follow certain rules.

(a)

What does the suffix '-ol' show in the name of a compound?

[1 mark]

(b)

Write the name of the alcohol with the molecular formula C4H9OH.

[1 mark]

(c)

Explain how the '-ol' ending helps to distinguish alcohols from other organic compounds.

[2 marks]

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

Show answer

(a) It means the compound is an alcohol (contains –OH). · must show Reference to –OH or alcohol

(b) Butanol · must show Correct name: butanol

(c) The '-ol' ending shows the compound has the alcohol functional group (–OH), so it is not an alkane or carboxylic acid. It helps chemists easily recognise alcohols in names. · must show Role of '-ol', distinction from other groups

Also accept: Butanol for C4H9OH

Common mistakes: Mistaking alkane names for alcohols; Omitting '-ol' in the name

Show mark scheme and worked solution

Marking points

B1 (a) · 1 mark · States '-ol' indicates alcohol/–OH group.

B2 (b) · 1 mark · Gives the correct name 'butanol'.

B3 (c) · 2 marks · Explains '-ol' ending marks out alcohols from other organic compounds by indicating the –OH group.

Worked solution

a) The '-ol' suffix tells you the compound is an alcohol, containing an –OH group.

b) The alcohol with formula C4H9OH is butanol.

c) The '-ol' ending in the name means it is not an alkane (which ends in '-ane') or an acid (which ends in '-oic acid'), so it is clearly an alcohol.