Q54 / 180 · KCET 2020 · Chemistry

If an aqueous solution of $\mathrm{NaF}$ is electrolysed between inert electrodes, the product obtained at anode is

  • A
    $\mathrm{F}_{2}$
  • B
    $\mathrm{H}_{2}$
  • C
    $\mathrm{Na}$
  • Correct answer
    D
    $\mathrm{O}_{2}$

Solution

Aqueous NaF, when electrolysed between inert electrodes we always get $\mathrm{O}_{2}$ at anode, as: At cathode $2 \mathrm{H}^{+}+2 e^{-} \longrightarrow \mathrm{H}_{2} \uparrow$ At anode $4 \mathrm{OH}^{-} \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}+\mathrm{O}_{2}+4 e^{-}$ Also, if any fluorine is liberated, that too reacts with $\mathrm{H}_{2} \mathrm{O}$. $2 \mathrm{~F}_{2}+2 \mathrm{H}_{2} \mathrm{O} \longrightarrow 4 \mathrm{HF}+\mathrm{O}_{2}$ So, ultimate product is oxygen.

Hence, the correct answer is option: 'D'.

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