How can one determine the concentrations of H3O and OH- ions from the pH of a solution?

To determine the concentrations of H3O and OH- ions from the pH of a solution, you can use the formula: pH -logH3O. From this, you can calculate the concentration of H3O ions. Since the product of H3O and OH- ions is constant in water (1.0 x 10-14 at 25C), you can then find the concentration of OH- ions by dividing this constant by the concentration of H3O ions.