Question

$NaHC{O}_3+C{H}_{3}COOH\to C{H}_{3}COONa+C{O}_2+H_{2}O$
This reaction used to test of carboxylic acid because :
(A) gas is confirmed when it turns lime water black
(B) gas is confirmed when it turns lime water milky
(C) gas is confirmed when it turns to water light green
(D) gas is confirmed when it turns to water brown

Answer 1

Hint: Carboxylic acids are more reactive organic compounds with good physical and chemical properties. The chemical structure of carboxylic acids consists of carbonyl group –C=O with hydroxyl group –OH. Due to the functional group-containing carboxylic acids are more reactive with polar compounds and salts.

Complete step by step answer:
To identify the presence of a carboxylic functional group during compound analysis in an organic chemistry laboratory, there are some important tests used to confirm the carboxylic functional group.
Anyone of the following tests can be carried out in the lab to detect the carboxyl function group in the given compound.
(1) Litmus test
(2) Sodium bicarbonate test
(3) Ester test

Litmus test: due to the presence of –OH group in the carboxylic functional group is acidic which turns blue litmus paper to red. The chemical reaction is:
$R-COOH+H_{2}O\to R-CO{O}^{-}+H_3{O}^{+}$

Sodium bicarbonate test: when carboxylic acid reacts with sodium bicarbonate is evolved with carbon dioxide gas is confirmed when it turns lime water milky.
$NaHC{O}_3+C{H}_{3}COOH\to C{H}_{3}COONa+C{O}_2+H_{2}O$

Ester test: In presence of sulphuric acid, carboxylic acid and alcohol give pleasant-smelling ester. This reaction is called esterification.
$R-COOH+R-OH\to RCOO-R(Ester)+H_{2}O$

Note: In the sodium carbonate test use acid-free alcohol so that will not interfere with the functional group of the given organic compound. This test is used to differentiate between carboxylic acids from phenol which does not respond to the sodium carbonate test.