How does the concentration of reactants affect cell potential in electrochemical cells?

The concentration of reactants plays a fundamental role in determining the cell potential of electrochemical cells, which is described by the Nernst equation. According to this relationship, the electromotive force (EMF) or cell potential is influenced by the concentrations of the reactants and products involved in the half-reactions.

As the concentration of reactants increases, the driving force for the reaction also typically increases, which tends to enhance the cell potential. This is because higher concentrations of reactants shift the equilibrium position of the electrochemical reaction towards the product side, promoting a greater extent of reaction and therefore a stronger overall potential.

In other words, when more reactant is available, the system can generate a higher voltage due to an increased likelihood of electron transfer. Conversely, if the concentration of reactants were to decrease, it would generally lead to a reduction in cell potential due to the same principle of equilibrium.

This makes option C correct, as it accurately reflects the typical outcome of increasing reactant concentrations on cell potential in electrochemical systems. The potential can significantly be influenced by the concentration of reactants, enhancing the ability to perform work in electrochemical reactions.