Question

In the electrolysis of aqueous sodium chloride with inert electrodes the products obtained at anode and cathode respectively are ______.

Options

• Cl₂ and Na

• O₂ and Na

• Cl₂ and H₂

• Na and Cl₂

Answer 1

In the electrolysis of aqueous sodium chloride with inert electrodes the products obtained at anode and cathode respectively are Cl₂ and H₂.

Explanation:

In the electrolysis of aqueous sodium chloride with inert electrodes, the products obtained at anode and cathode respectively are Cl₂ and H₂·

The solution contains four ions Na⁺, Cl^-, H⁺, `bar"O""H"`.

Following reaction takes place:

At cathode -

\[\ce{Na+(aq) + e- -> Na(s);}\]  `"E"_("Na"^+//"Na")` = - 2.71 V

\[\ce{2H2O(l) + 2e- -> H2(g) + 2 \bar{\text{O}}H(aq)}\]   `"E"_("H"_2"O"+//"H"_2)` = - 0.83 V

At anode -

\[\ce{2Cl- (aq) -> Cl2(g) + 2e-; E^\circ_{Cl^-/Cl_2} = - 1.36 V}\]

\[\ce{2H2O2(l) -> O(g) + 4H- (aq) + 4e^-; E^\circ_{H_2O/O_2}= - 1.23 V}\]

\[\ce{E^\circ_{H_2O/O_2} > E^\circ_{Na^+/Na^+}}\]. So, H₂ is formed at cathode.

Whereas \[\ce{E^\circ_{H_2O/O_2} > E^\circ_{Cl^-/Cl_2}}\]. So, Cl₂ is formed at anode.