[uzi4u2]

 Hello people
I have a small calculation problem that for some reason eludes me 

What is the PH of a solution 0.81M acid and 0.35M of its conjugated base if the ionization constant is 1.8x10^-5     


Thank you guys for all the help , i dont need the answer i need more the way of solving it

[english]

1.  We need to know what acid-base pair you have.
2.  Write a reaction equation(s).
3.  Make ICE tables.
4.  You will use the quadratic equation in your calculation.


The reason I've been ambiguous is because you haven't shown an attempt.  Your book undoubtedly provides example problems similar to this one.  Consult your book first, teacher second, then us.

[Yggdrasil]

Another option is to use the Henderson-Hasselbalch equation.

[Borek]

HH equation. ICE table leads nowehere in this case - you have to assume there is NO further change to the system. This is classical buffer question.

[uzi4u2]

thanks alot guys