An ether solution contains benzoic acid, phenol and toluene. It is shaken with dilute aqueous NaHCO3 (pK_a of H2CO3 is 6.4; benzoic acid 4.20; phenol 10.0). The species transferred into the aqueous layer is

benzoic acid, as sodium benzoate

JEE Main levelSingle correct optionDifficulty 2 of 3g2119

An ether solution contains benzoic acid, phenol and toluene. It is shaken with dilute aqueous $NaHCO X_{3}$ ( $p K_{a}$ of $H X_{2} CO X_{3}$ is 6.4; benzoic acid 4.20; phenol 10.0). The species transferred into the aqueous layer is

Only an acid with

p K_{a}

well below 6.4 is converted into its salt by

HCO X_{3} X^{-}

. Benzoic acid (

lo g K = 6.4 - 4.20 = 2.2

) is, whereas phenol (

lo g K = 6.4 - 10.0 = - 3.6

) is not and toluene is not acidic. Only sodium benzoate dissolves in water.