In the electrolysis of aqueous sodium chloride solution, which of the half cell reaction will occur at anode?

Question

In the electrolysis of aqueous sodium chloride solution, which of the half cell reaction will occur at anode?, $ N a^{+}(a q)+e^{-} \rightarrow N a(s) ; E_{\text {cell }}^{\circ}=-2.71 $ volts, $ 2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow \mathrm{O}_{2}+4 \mathrm{H}^{+}+4 e^{-} ; \mathrm{E}_{\text {cell }}^{\circ}=1.23 $ \$volts, $ H^{+}(a q)+e^{-} \rightarrow \frac{1}{2} H_{2} ; E_{\text {cell }}^{\circ}=0.00 $ volts, $ \mathrm{Cl}^{-}(a q) \rightarrow \frac{1}{2} \mathrm{Cl}_{2}+e^{-} ; E_{\text {cell }}^{\circ}=1.36 $ volts

MARKS App · Accepted Answer

In water sodium chloride ionizes as $ N a C l(a q) \rightleftharpoons N a^{+}(a q)+C l^{-}(a q) $ water also dissociates into ions, though to very slight degree as, $ \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightleftharpoons \mathrm{H}^{+}(a q)+\mathrm{OH}^{-}(a q) $ Thus, the aqueous solution of sodium chloride contains $ \mathrm{N} a^{+}, \mathrm{H}^{+}, \mathrm{OH}^{-} $and $ \mathrm{Cl}^{-} $ions. When electric current is passed through the solution, $ \mathrm{Cl}_{2} $ gas evolved at anode and hydrogen is evolved at the cathode. The resulting solution contains $ \mathrm{Na}^{+} $and $ \mathrm{OH}^{-} $ions. Oxidation of $ \mathrm{Cl}^{-} $ions and $ \mathrm{H}_{2} \mathrm{O} $ is possible at anode but, standard electrode potential of $ \mathrm{Cl}^{-} $is more, therefore, $ \mathrm{Cl}^{-} $will oxidized at anode.

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