What determines the extent of a reaction in terms of reactant concentration?

Le Chatelier's Principle is fundamentally about understanding how a system at equilibrium responds to changes in concentration, temperature, or pressure. According to this principle, if an external change is applied to a system at equilibrium, the system will respond by shifting in a direction that counteracts the change.

When considering reactant concentration specifically, if the concentration of reactants is increased, the system will shift to produce more products, thus favoring the forward reaction. Conversely, if the concentration of reactants decreases, the equilibrium will shift in the direction of the reactants to re-establish equilibrium.

This principle is crucial in predicting how adjustments to the concentrations of reactants or products can impact the extent of a chemical reaction and the position of equilibrium. It allows chemists to manipulate conditions to maximize product formation in various applications, such as synthesis or reaction optimization.

In contrast, the other theories mentioned focus on different aspects of chemical reactions. The ideal gas law relates to the behavior of gases, Arrhenius theory discusses the temperature dependence of reaction rates, and reduction potential pertains to the tendency of a substance to gain electrons in redox reactions rather than directly to changes in reaction concentrations or equilibrium.