What is the primary factor that influences the voltage generated in electrochemical cells?

The primary factor that influences the voltage generated in electrochemical cells is indeed the types of reactants and their concentrations. The electrochemical potential, which is directly related to the voltage produced, depends significantly on the specific chemical reactions occurring at the electrodes. Each reactant has a characteristic standard electrode potential based on its ability to gain or lose electrons.

When different reactants are used, they can create varying levels of driving force for the electrochemical reactions. Higher concentrations of reactants can lead to greater reaction rates and voltage output according to Nernst's equation, which quantitatively relates the concentration of reactants to the potential of the cell. This means that adjustments in the types and concentrations of the substances involved can lead to significant changes in the cell's voltage.

For example, if one electrode is involved in a reaction with a high standard reduction potential while the other involves a reaction with a much lower standard reduction potential, the difference between these two potentials determines the overall voltage output of the cell. Thus, the correct understanding of how the types and concentrations of reactants influence voltage is crucial in electrochemistry.