1. P2- + H2O  HP- + OH- , hydrolysis
CH 17 #80
g KPH x 1 mol KPH = = mol KPH
WHICH MEANS THAT THERE ARE MOL OF P2- AT EQ
KPA is an amphoteric conjugate which is acting as an acid in this reaction.
P2- + H2O  HP- + OH- , hydrolysis
P2-
H2O
HP-
OH-
0.0239 -X X X

2. P2-
H2O
HP-
OH-
0.0239 -X X X
Kb = [HP-][OH-] = Kw = 1.0 x = 3.23 x 10-9 = 3.2 x 10-9
[P2-]
Kb = [HP-][OH-] = (x) = X = [OH-] = 8.8 x 10-6 molar
[P2-] ( X)
pOH- = 5.06 : pH = 14 – 5.06 = 8.94 thymol blue or change neat this pH.