Drawing and naming the carboxylic acids

4 marks · Normal

This question is about naming carboxylic acids.

(a)

Give the name of the carboxylic acid with molecular formula C4H8O2.

[1 mark]

(b)

Write the name and structural formula of the carboxylic acid with molecular formula CH2O2.

[2 marks]

(c)

State how you determine the name of a straight-chain carboxylic acid from its molecular formula.

[1 mark]

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) butanoic acid

(b) methanoic acid; HCOOH · must show name and formula given

(c) Count all carbon atoms (including the one in the COOH group) and use the appropriate alkane prefix with 'anoic acid'. · must show explanation of counting all carbons, mention of alkane base name + 'anoic acid'

Show mark scheme and worked solution

Marking points

B1 (a) · 1 mark · Gives name: butanoic acid

B2 (b) · 1 mark · Gives name: methanoic acid

B3 (b) · 1 mark · Gives structural formula: HCOOH or correct fully displayed formula

B4 (c) · 1 mark · Correctly states carboxylic acid name comes from counting all carbon atoms (including COOH C) and using alkane base name + 'anoic acid'

Worked solution

a) The carboxylic acid with molecular formula C4H8O2 is butanoic acid.

b) The name is methanoic acid. Structural formula: HCOOH.

c) To name a straight-chain carboxylic acid, count all carbon atoms in the formula (including in –COOH), use the appropriate alkane prefix, and add 'anoic acid'.