DP Chemistry (last assessment 2024)

Question 20N.2.hl.TZ0.e

[Maximum mark: 2]

20N.2.hl.TZ0.e

A student performs a titration to determine the concentration of ethanoic acid, ${CH}_{3} COOH$ , in vinegar using potassium hydroxide.

In a titration, $25.00 {cm}^{3}$ of vinegar required $20.75 {cm}^{3}$ of $1.00 mol {dm}^{- 3}$ potassium hydroxide to reach the end-point.

Calculate the concentration of ethanoic acid in the vinegar.

[2]

Markscheme

$« n (KOH) = 0.02075 {dm}^{3} \times 1.00 mol {dm}^{- 3} = » 0.0208 « mol »$ ✔

$« n (KOH) = n ({CH}_{3} COOH) »$
$« [{CH}_{3} COOH] = \frac{0.0208 mol}{0.02500 {dm}^{3}} = » 0.830 « mol {dm}^{- 3} »$ ✔

Award [2] for correct final answer.

Examiners report

Like with other calculations in this exam, the majority of candidates could correctly determine a concentration from titration data.

Syllabus sections