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Answer the following.
Write chemical tests to distinguish between the following pairs of compounds: Acetaldehyde and…
Write chemical tests to distinguish between the following pairs of compounds:
(a)[1.0]
Acetaldehyde and acetone
(b)[1.0]
Acetic acid and benzaldehyde
Answer
Answer (a)
AITollen's test: Warm each compound with ammoniacal silver nitrate (Tollen's reagent). Acetaldehyde gives a shining silver mirror (or grey-black precipitate of $\text{Ag}$), whereas acetone does not react.
$\text{CH}_3\text{CHO} + 2[\text{Ag}(\text{NH}_3)_2]^+ + 3\text{OH}^- \longrightarrow \text{CH}_3\text{COO}^- + 2\text{Ag}\downarrow + 4\text{NH}_3 + 2\text{H}_2\text{O}$
Answer (b)
AISodium bicarbonate ($\text{NaHCO}_3$) test: Add saturated aqueous $\text{NaHCO}_3$ solution to each compound. Acetic acid produces brisk effervescence due to the evolution of $\text{CO}_2$ gas, whereas benzaldehyde shows no effervescence.
$\text{CH}_3\text{COOH} + \text{NaHCO}_3 \longrightarrow \text{CH}_3\text{COONa} + \text{H}_2\text{O} + \text{CO}_2\uparrow$
From ISC 2026 Chemistry Paper 1, question 9(i).
Check your working with the Distinguish two organic compounds: the chemical tests that tell two organic compounds apart, with what each one shows.