Question

The number of species of the following that can act both as Bronsted acids and bases is $HCl,Cl{O}_4^{-},{}^{-}OH,H^{+},H_{2}O,HS{O}_4^{-},S{O}_4^{2-}$, $H_{2}S{O}_4,C{l}^{-}$

• A. 4
• B. 3
• C. 1
• D. 2

Answer 1

Answer: (D)

(i) $HCl\to H^{+}+C{l}^{-}$ (Bronsted acid)

(ii) $Cl{O}_4^{-}+H^{+}\to HCl{O}_4$ (Bronsted base)

(iii) $\bar{O}H+H^{+}\to H_{2}O$ (Bronsted base)

(iv) $H_3{O}^{+}\to H^{+}+H_{2}O$ (Bronsted acid)





(vii) $H^{+}+S{O}_4^{2-}\to HS{O}_4^{-}$ (Bronsted base)

(viii) $H_{2}S{O}_4\to H^{+}+HS{O}_4^{-}$ (Bronsted acid)

(ix) $C{l}^{-}+H^{+}⟶HCl$ (Bronsted base)

Hence, $H_{2}O$ and $HS{O}_4^{-}$ (two species act as acid as well as base)