Question

Among the following compounds, the one(s) that gives (give)effervescence with aqueous $NaHCO_3$ solution is (are)
$\underset{I}{(CH_3CO)_2O}\,\,\,\,\,\,\underset{II}{CH_3COOH}\,\,\,\,\,\,\, \underset{III}{PhOH}\,\,\,\,\,\, \underset{IV}{CH_3COCHO}$

• A. I and II
• B. I and III
• C. only II
• D. I and IV

Answer 1

Answer: (A)

Only carboxylic acids and their derivatives like anhydride are capable to give effervescence with aqueous $NaHCO _{3}$ solution, because they are more acidic as compared to $H _{2} CO _{3}$ (carbonic acid).
$ II CH _{3} COOH + NaHCO _{3} \longrightarrow CH _{3} COONa + H _{2} O + CO _{2} $
$ I \left( CH _{3} CO \right)_{2} O + 2 NaHCO _{3} \longrightarrow 2 CH _{3} COONa + H _{2} O + CO _{2} $