Class 12 NEET Chemistry Aldehydes, Ketones And Carboxylic Acids Part 2

Concept:Acetate salts react with dilute $\mathrm{H}_2\mathrm{SO}_4$ to produce acetic acid vapour, which has a characteristic vinegar smell and is acidic.Chemical Equation / Formula:$2\,\mathrm{CH}_3\mathrm{COONa} + \mathrm{H}_2\mathrm{SO}_4 \to \mathrm{Na}_2\mathrm{SO}_4 + 2\,\mathrm{CH}_3\mathrm{COOH}$ (vapour)Explanation:• Dilute $\mathrm{H}_2\mathrm{SO}_4$ provides $\mathrm{H}^+$ ions.• With acetate ion ($\mathrm{CH}_3\mathrm{COO}^-$), it forms acetic acid ($\mathrm{CH}_3\mathrm{COOH}$).• Acetic acid is volatile, colourless, and smells like vinegar.• Its acidic nature turns blue litmus red.• Other anions do not match: sulphide gives $\mathrm{H}_2\mathrm{S}$ (rotten egg smell); carbonate gives $\mathrm{CO}_2$ (odourless); sulphate does not react with dilute $\mathrm{H}_2\mathrm{SO}_4$.Shortcut:The smell of vinegar is a direct confirmatory test for acetate ion in salt analysis.Answer:Acetate, $\mathrm{CH}_3\mathrm{COO}^-$ (Option C)