Question

A corrosion cell consisting of Zinc and Nickel is formed. Which of the following statement is true? (A) Nickel will act as Anode (B) Zinc will act as Anode (C) Either metal can act as Anode (D) Corrosion will not occur

Answer 1

Answer: B) Zinc will act as Anode

Explanation:

Standard reduction potential of zinc and nickel are:

$E^0_{[Zn^{2+}/Zn]}= -0.76V$

$E^0_{[Ni^{2+}/Ni]}=-0.25V$

Here Zinc undergoes oxidation by loss of electrons, thus act as anode as it has more negative reduction potential.

Nickel undergoes reduction by gain of electrons and thus act as cathode. as it has less negative reduction potential.

$Zn+Ni^{2+}\rightarrow Zn^{2+}+Ni$

$E^0_{cell}=E^0_{cathode}- E^0_{anode}$

Where both $E^0$ are standard reduction potentials.

$E^0=E^0_{[Ni^{2+}/Ni]}- E^0_{[Zn^{2+}/Zn]}$

$E^0=0.25-(-0.76V)=0.51V$

As the emf is positive, the reaction is spontaneous and reaction will occur.

Thus Zinc will act as anode.