Who can solve this strange concentration problem?

Question

The pH of a 0.02 M solution of an unknown weak base is 8.1. What is the pKb of the unknow solution
(I think it is referred to pKb=-logKb, but I am not sure how to solve it)

Answer 1

First of all there is no such thing as pKb of a solution (only of a base).
Second it is impossible to solve if you don't know the valency of your base. Assuming it is monovalent:

________________MOH <=> M(+) + OH(-)
initial concentration__C
Dissociating________x
Producing_________________x______x
at Equilibrium ______C-x_____x______x

Kb=[M(+)]/[OH(-)]/[MOH]=x*x/(C-x)=x^2/(C-x)

since pH=8.1 pOH=14-8.1=5.9 and
[OH(-)]=10^(-pOH)=1.26*10^-6

But we said that [OH(-)]=x and know that C=0.02 M

Thus pKb=-logKb=-log(x^2/(C-x))=
=-log((1.26*10^-6)^2/(0.02-1.26*10^-6)=
=10.1

Stupid site doesn't show everything I am writing; just put the pointer over "..." to read the missing parts

Answer 2

ok, having intercourse with somebody you don't be conscious of is a stupid pass no count what their determination of occupation is, prostitution on the different hand is out precise risky many times, those human beings have intercourse with assorted "companions" as many cases an afternoon as they are able to slot in, if any of them are donning any STD there's a competent possibility that the prostitute will p.c.. some thing up quicker or later, even in states like Nevada the place Prostitution is criminal with month-to-month licensing and verify united statesit's nonetheless no longer appropriate and you nonetheless have an greater possibility of contracting some thing you probably did no longer pay for, its ultimate to in basic terms have intercourse with an enhanced half you're in a relationship with.

Answer 3

okay, I could have probably done this question a few months ago. But I've forgotten a lot of chem, so my advice would be to look up the Henderson-Hasselbalch equation and try using that

Answer 4

Yea my calculator also packed up.

Answer 5

and that is y i cheated in HS chem.

Answer 6

i can