Consider the concentration cell:

c. Indicate what happens to the concentration of Pb²⁺ in each half-cell.

Key Concepts

Concentration Cell

A concentration cell is a type of galvanic cell where the electrodes are made of the same material but are immersed in solutions of different concentrations. The potential difference arises from the concentration gradient, driving the spontaneous flow of electrons from the anode (lower concentration) to the cathode (higher concentration). This process continues until the concentrations equalize, demonstrating the relationship between chemical potential and concentration.

Nernst Equation

The Nernst equation relates the cell potential to the concentrations of the reactants and products in an electrochemical cell. It is expressed as E = E° - (RT/nF) ln(Q), where E is the cell potential, E° is the standard cell potential, R is the gas constant, T is the temperature in Kelvin, n is the number of moles of electrons transferred, F is Faraday's constant, and Q is the reaction quotient. This equation helps predict how changes in concentration affect the cell's voltage.

Electrode Reactions

In a concentration cell, the electrode reactions involve the oxidation and reduction of the same species at different concentrations. At the anode, the species in lower concentration loses electrons (oxidation), while at the cathode, the species in higher concentration gains electrons (reduction). This transfer of electrons is what generates electrical energy, and the concentration of the ions in each half-cell will change as the cell operates, with the anode's concentration decreasing and the cathode's concentration increasing.