[nisek]

In a mixture solution of 0.05 mol L-1 NiCl2, 0.05 mol L-1 ZnCl2, and 0.5 mol L-1
HBO3 at pH 3.5, use Nernst equation to work out the potential window, in which a
thin film of pure nickel can be electrodeposited onto the steel substrate from this
mixture solution at 25 oC, and show the steps of your calculations. (The standard
reduction electrode potentials for redox couples Ni2+/Ni and Zn2+/Zn are -0.250 V
and -0.763 V vs Standard Hydrogen Electrode (SHE), respectively. R = 8.314 J (mol
K)-1, F = 96500 C mol-1).

I have so far managed to determine the overall chemical potential but don't know how to do the rest

[Borek]

Show your work and we will start from there.

[hirwani1]

So the reaction is Ni + 2Cl(-) --> Ni(+2) + Cl2, reaction quotient would be [Ni+2]/[Cl-]² Which is 0.01/(0.01)² = 100. So my final answer is 1.61 - (0.059/2 × log 100) which is = 1.61-0.059 = 1.55

[Hunter2]

The equation is wrong

You have on reactant side 2 negative charges and on product side 2 positive.

Here we have only

Ni2+ + 2 e- => Ni deposit of Nickel

2 H+ + 2e- => H2 Standard Hydrogen electrode

The chloride is spectator.