Submitted by Adam Johnson / Harvey Mudd College on Wed, 10/01/2008 - 11:56
Forums

I have in my notes from 9 years ago, this handy equation for prediction of pKa's for oxyacids.  I was using Huheey at the time, and the equation isn't there.  In fact, I can't find it ANYWHERE.  I am certain that I did not develop this equation.... Does anyone recognize it?  Where is it from?  And which electronegativity values does it use?

 

pKa ~ 10.5 -5n - (chi)X

for

(HO)mX(O)n;  chi is the electronegativity of the central atom X, n is the number of oxos.

I have found several other equations, but none of them take into account the central element...

 

its driving me crazy!

Adam

Nancy Williams / Scripps College, Pitzer College, Claremont McKenna College

Well, not exactly Pauling's per se, but his textbook popularized this one. It's Eqn. 9.46 on p. 329 of Huheey, Keiter, and Keiter, 4th Ed.

Sun, 10/12/2008 - 17:52 Permalink
Adam Johnson / Harvey Mudd College

In reply to by Nancy Williams / Scripps College, Pitzer College, Claremont McKenna College

ok, I looked through HKK since that was the book I was using at the time, and totally missed it.  That MUST be where I got it.  thanks!

Feeling old,

Adam

Wed, 10/15/2008 - 01:07 Permalink