For the reaction 2 Cr(s) + 3 Pb²⁺(aq) ⟶ 3 Pb(s) + 2 Cr³⁺(aq), what is the value of n in the Nernst equation?

Question

For the reaction 2 Cr(s) + 3 Pb²⁺(aq) ⟶ 3 Pb(s) + 2 Cr³⁺(aq), what is the value of n in the Nernst equation?

Answer 1

n in the Nernst equation is the number of electrons that are transferred during the reaction.

Looking at the 1/2 reactions for this oxidation/reduction, we have...

2Cr(s) ==> 2Cr³⁺ + 6e- ... oxidation half reaction

3Pb²⁺ + 2e- ==> 3Pb(s) ... reduction half reaction

We have to multiply the reduction half reaction by 3 in order to equalize the electrons so that SIX electrons are transferred.

So, the value of n in the Nernst equation will be 6.