7.57 If 0.561 g of KOH is dissolved in water to give 200 mL of solution at 298 K. Calculate the concentrations of potassium, hydrogen and hydroxyl ions. What is its pH?

[KOHaq]=0.56115g/L=2.805g/L=2.805×156.11M=.05 MKOH(aq)K(aq)++OH-(aq)[OH-]=.05 M =[K+][H+][H-]=Kw[H+]=Kw[OH-]=10-140.05=2×10-13MpH=12.70