[mol]

 If an amphiprotic anion is given say HPo4^ 2-, how should I find the pH value for a given solution?
say for eg. if  a solutn of K2HPO4 is given and  the pK1, pK2 and pK3 all 3 values for H3PO4 acid  are known.

Should I take  average of 1 st and 3 rd value ie.(pK1 and pK3) to find the ph of 2nd one ( but it is already a known one!) or should I just plug in the pK2 value n find the pH directly? Is there any specific formula how to find the pH of an amphiprotic anion? Could anyone pls guide on this?
thanks

[Borek]

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

[mol]

thanks for the link. It helps.