Not a Concentration Cell

There are several types of electrochemical cells, including concentration cells. A concentration cell is a type of electrochemical cell where the concentration of a reactant or product is different between the two half-cells, resulting in a potential difference. However, one of the following options is not a concentration cell.

Answer: B Pd,(Hg)∣Pd2 ∣(Hg),Pd (C1​) (M) (C2​)

Explanation:

To determine which of the options is not a concentration cell, we need to understand what a concentration cell is. A concentration cell is an electrochemical cell that consists of two half-cells that have the same electrodes, but different concentrations of the same electrolyte. The potential difference between the two half-cells is due to the difference in concentration of the electrolyte.

Let's examine each option to determine which one is not a concentration cell.

A. Pt,H2​∣HCl∣H2​(g),Pt (p1​) (M) (p2​)

This is a concentration cell because the two half-cells have the same electrodes, but different concentrations of HCl.

B. Pd,(Hg)∣Pd2 ∣(Hg),Pd (C1​) (M) (C2​)

This is not a concentration cell because the half-cells do not have the same electrolyte. One half-cell contains Pd2+ ions, while the other half-cell contains Hg. Therefore, there is no difference in concentration of the same electrolyte.

C. Zn(S)∣Zn2 ∣∣Cu2 ∣Cu (M1​) (M2​)

This is a concentration cell because the two half-cells have the same electrodes, but different concentrations of Zn2+ ions.

D. Ag(S),AgCl(s)∣HCl∣∣HCl∣AgCl(s)∣Ag(s) (M1​) (M2​)

This is a concentration cell because the two half-cells have the same electrodes, but different concentrations of Ag+ ions and Cl- ions.

In conclusion, option B is not a concentration cell because the half-cells do not have the same electrolyte.