find the quotient of [HIO3]/[IO3]?

Question

given that the pKb of iodate ion IO3- is 13.83, find the quotient [HIO3]/[IO3-] in a solution of sodium iodate at pH 6.00

Answer 1

IO3- + H2O <==> HIO3 + OH-
Kb = [HIO3]*[OH-]/ [IO3-]
13.83 = pKb = -log(Kb)
= -log([HIO3]/ [IO3-]) - log([OH-])
= -log([HIO3]/ [IO3-]) + pOH
=-log([HIO3]/ [IO3-]) + 8.00
5.83 = -log([HIO3]/ [IO3-])
[HIO3]/ [IO3-] = 10^(-5.83)