SAND EQUATION

"An equation relating current density, transition time, and concentration of the reactant in a chronopotentiometric experiment, assuming that the current is sufficiently large to immediately result in diffusion limiting conditions. The equation is valid only for planar electrodes in unstirred solution. The product of the current density and the square root of the transition time divided by the concentration is a constant. The constant is proportional to the square root of the diffusion coefficient of the reactant. Because the equation was derived for an unstirred solution, it ceases to be valid once natural convection starts. "