Question

An electrochemical cell is composed of pure nickel and pure iron electrodes immersed in solutions of their divalent ions. If the concentrations of Ni2+ and Fe2+ ions are 0.002 M and 0.40 M, respectively, what voltage is generated at 25°C? (The respective standard reduction potentials for Ni and Fe are −0.250 V and −0.440 V.) (A) −0.76 V (B) −0.26 V (C) +0.12 V (D) +0.76 V

Answer 1

Answer:C  0.12 V

Explanation:

Given

Concentration of $Fe^{2+} M_1=0.40 M$

Concentration of $Ni^{2+} M_2=0.002 M$

Standard Potential for Ni and Fe are $V_2=-0.25 V$  and $V_1=-0.44 V$

$\Delta V=V_2-V_1-\frac{0.0592}{2}\log (\frac{M_1}{M_2})$

$\Delta V=-0.25-(-0.44)-\frac{0.0592}{2}\log (\frac{0.4}{0.002})$

$\Delta V=0.12\ V$