The approach to equilibrium of a reaction that is first-order is given by

Where A₀, is initial concentration of reactant A (mol L^-1), t is time (s), and k₁ and k₂ are rate constants (s^-1).

To graph the concentration of the reactants enter the parameters (i.e., A₀, k₁, k₂) and hit New Plot. Up to 3 plots pairs can be displayed at one time. The Clear button will remove all plots. To see the parameters for each plot hit the Legend on/off button. The Redraw button will refresh the graph. This is useful when the function domain (i.e., t ) has been changed. To see the value of each plot at a given point, move your cursor to the desired location then click and hold.