Consider the following redox reaction taking place in acidic medium BH₄⁻ + ClO₃⁻ → H₂BO₃⁻ + Cl⁻ and find the value of n in the Nernst equation.
Q. Consider the following redox reaction taking place in acidic medium

BH4− (aq) + ClO3− (aq) → H2BO3− (aq) + Cl− (aq)

If the Nernst equation for the above balanced reaction is

Ecell = E°cell − (RT / nF) ln Q,

then the value of n is ____ . (Nearest integer)

Correct Answer: 24

Explanation

To find the value of n, we must balance the given redox reaction in acidic medium and determine the total number of electrons transferred.

For boron in BH4−, oxidation state changes from −3 to +3 in H2BO3−, which corresponds to a loss of 6 electrons per boron atom.

For chlorine in ClO3−, oxidation state changes from +5 to −1 in Cl−, which corresponds to a gain of 6 electrons per chlorine atom.

On balancing the complete redox reaction in acidic medium, the overall reaction involves transfer of 24 electrons.

Therefore, the value of n used in the Nernst equation is 24.

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