general: pH = -log
c(H+)Â Â Â Â Â Â Â Â pOH = -log
c(OH-)
c(H+) * c(OH-) = 10-14
pH + pOH = 14
solution A: c (OH-) = 10-14 / c(H+) =
5*10-12
                Â
pH = -log (0.002) = 2.7
               Â
pOH = 14-2.7 = 11.3
solution B: c (H+) = 10-14 / c(OH-) =
2.5*10-10
                    Â
pH = 9.6
              Â
pOH = 4.4
solutionC: c (H+) = 4.6*10-11
             Â
c (OH-) = 2.2*10-4
            Â
pOH = 3.66
solutionD: pH = 10.01
             Â
c(H+) = 9.8*10-11
                Â
c(OH-) = 1.0*10-4
