Please HELP WITH CHEMISTRY! Best answer to best answer.?

Question

Okay, I need help with this problem in chemistry. Your help Is MUCH appreciated.

What is the pH of .0180 M H3PO4? What is the concentration of PO4?

Ka1= 7.5 x 10 -3(power)
Ka2= 6.2 x 10 -8(power)
Ka3= 4.8 x 10 -13(power)

Okay I can find the pH of .0180.
But I need help finding the concentration of PO4
This is what I have so far:

H3PO4 + H2O <=======> H30 + H2PO4 Ka1= 7.5 x 10 -3
H2PO4 + H2O <=======> H30 + HPO4 Ka2= 6.2 x 10 -8
HPO4 + H2O <=======> H30 + PO4 Ka3= 4.8 x 10 -13
--------------------------------------------------------
H3PO4 + 3H2O <=======> H2PO4 + PO4

Next:
H3PO4 + 3H2O <=======> 3H3O + PO4
I .0180 X 0 0
C -x X +x +x
E ~ .0180 X x x

(x)(x)
------- = whatever Ka is
.0180

I need to know if I have the right idea. I

My teacher wrote this on my paper.

H3PO4 <========> H + H2PO4
.0180 0 0
-x -x -x
.0180-x x x

BUt this equasion doesn't have PO4 in it, so I don't really see how it helps... If you could please explain why my work is wrong or right that would really be jelpful.

Oops, I didn't realize that yahoo kept messing my equasions up. If you could im me that would be great! I really need to figure out this problem, we have a test on this stuff tomorrow.

Answer 1

This is to hard to read.
Bad on the eyes indeed :)