What is wrong with the following statement: The best...

Name: Problem 24, Chapter 18: Chemistry
Uploaded: 2020-05-14T19:04:44-08:00
Duration: 59 s
Channel: David Collins
Description: What is wrong with the following statement: The best concentration cell will consist of the substance having the most positive standard reduction potential. What drives a concentration cell to produce a large voltage?

What is wrong with the following statement: The best concentration cell will consist of the substance having the most positive standard reduction potential. What drives a concentration cell to produce a large voltage?

Key Concepts

Standard Reduction Potential

The standard reduction potential measures the tendency of a chemical species to gain electrons under standard conditions (typically 1 M concentration, 1 atm pressure, and 25°C). In concentration cells, this concept is not directly relevant because the electrodes are identical in terms of their standard potential; the driving force for the cell's voltage comes solely from the concentration gradient between the two half-cells.

Nernst Equation

The Nernst equation describes how the cell potential adjusts based on the concentrations of the reactants and products. For a concentration cell, the equation shows that the electromotive force (EMF) is proportional to the logarithm of the ratio of the concentrations between the two half-cells. Thus, a larger concentration difference will lead to a higher voltage, highlighting that the cell’s performance is determined by this gradient rather than by the intrinsic standard reduction potential.

Concentration Cell

A concentration cell is an electrochemical cell in which both electrodes are made of the same material and involve the same redox couple, but they are immersed in solutions of different concentrations. The cell potential in a concentration cell is driven entirely by the difference in the concentration of the species involved, rather than by inherent differences in the chemical nature or standard reduction potentials of different substances.

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