how to find pH from K2HP04?

Question

Hi.
How do I calculate this...
The pH of a 0.100M solution of K2HPO4?

the Dissociation constant:
H3PO4
K1 : 7.1^10-3
K2: 6.2^10-8
K3: 4.5^10-13

Answer 1

You will find a free tutorial at the site below

http://www.chembuddy.com/?left=pH-calculation&right=pH-amphiprotic-salt

Especially if you go at the bottom of the page you will find a table for Na2HPO4 (it is the same as the potassium salt) in which 0.1 M gives pH=9.72. So you can follow the methodology described and then verify the result.