The label on a bottle of vinegar claims that it contains at least 50 g of ethanoic acid, CH3COOH\mathrm{CH_{3}COOH}CH3COOH, in every 1 dm3\mathrm{dm^{3}}dm3.
A student uses a pipette to put 10.0 cm3\mathrm{cm^{3}}cm3 of the vinegar into a conical flask. The student adds phenolphthalein and titrates the vinegar with 0.500 mol dm−3\mathrm{mol\,dm^{-3}}moldm−3 sodium hydroxide solution.
CH3COOH(aq)+NaOH(aq)→CH3COONa(aq)+H2O(l)\mathrm{CH_{3}COOH(aq)} + \mathrm{NaOH(aq)} \rightarrow \mathrm{CH_{3}COONa(aq)} + \mathrm{H_{2}O(l)}CH3COOH(aq)+NaOH(aq)→CH3COONa(aq)+H2O(l)
Name the salt formed in this reaction.
The table shows the student's results.
| Titration | Rough | 1 | 2 | 3 |
|---|---|---|---|---|
| Volume of sodium hydroxide solution / cm3\mathrm{cm^{3}}cm3 | 17.10 | 16.55 | 16.95 | 16.65 |
Calculate the mean titre using the concordant results only.
Calculate the concentration of ethanoic acid in the vinegar, in mol dm−3\mathrm{mol\,dm^{-3}}moldm−3.
Determine whether the vinegar meets the claim on the label. Relative formula mass of CH3COOH=60\mathrm{CH_{3}COOH} = 60CH3COOH=60
A solution of hydrochloric acid with the same concentration as the vinegar has a lower pH. Explain why.
43 exam-style questions on Edexcel GCSE Chemistry 10.4 Alcohols and carboxylic acids, covering 10.4.1 Alcohols and the -OH functional group, 10.4.2 Carboxylic acids and the -COOH functional group, 10.4.3 Oxidation of alcohols and homologous series, and 10.4.4 Fermentation and fractional distillation of ethanol. Each one has a worked solution and a mark scheme showing where the marks go.