Typically, the concentration of hydronium, H+, or hydroxide,OH- , ions in an aqueous solution is less than 1M . It is not uncommon to have hydronium ion concentrations that are much smaller, such as 2.60*10^-5. , PH therefore, is a convenient way to restate the hydronium concentration. PH is equal to the negative log of a hydronium ion concentration in solution: