Question

A solution of nickel sulphate in which nickel rod is dipped is diluted 10 times. The reduction potential of Ni at 298 K

• A. decreases by 60 mV
• B. decreases by 30 mV
• C. increases by 60 mV
• D. increases by 30 mV

Answer 1

The correct option is

B

decreases by 30 mV

$E=E^o-\frac{0.059}{2}log\left[{Ni}^{2+}\right]$

$E^1=E^o-\frac{0.059}{2}log\frac{\left[N{i}^{2+}\right]}{10}$

$E-E^1=-\frac{0.059}{2}log\frac{\left[{Ni}^{2+}\right]}{\frac{{Ni}^{2+}}{10}}$

$E-E^1=-0.0295log10$

$=-0.0295or-0.03$

$E^1=E+0.03V$

$E^1=E+30mV$

$Hencewemaysaythatthepotentialof{Ni}^{2+}electrodeincreasesby30mV$

As the solution is diluted, new concentration would be 10 times lower, decreasing the voltage by 30 mV.