help again with chemistry-determining Kb for base?

N

n0wandf0rever

New member
Problem:
A 0.140 M solution of a weak base has a pH of 11.28. Determine Kb for the base.

So I tried:
11.28=x+log(.140)
x=pKa=12.1339

then:
pKa=-logKa
10^-12.1339=7.35e-13

Ka*Kb=Kw
Kw=1x10^-14
therefore:
1x10^-14/7.35x10^-13=.01361

and that's not the right answer at all
so please help--what am I doing wrong?
 
Back
Top