The pH of an aqueous Na OH solution is 1283 what is the hydr

The pH of an aqueous Na OH solution is 12.83. what is the hydrogen ion concentration of this solution? PLEASE BE DESCRIPTIVE!

ALSO: What volume of .250 M KCl will completely react with 50.0 mL OF .115 m Pb(NO3)2?

2KCl+Pb(NO3)2>PbSO4+2KNO3

Solution

1)

pH == 12.83

H+ 10^-pH= 1.479* 10-13 M

2)

0.250* V= 0.05*0.115

V= 23 ml