## Bigger or Smaller Acidity Constant in Cations?

Acidity $K_{a}$
Basicity $K_{b}$
The Conjugate Seesaw $K_{a}\times K_{b}=K_{w}$

Silvino Jimenez 1A
Posts: 52
Joined: Fri Sep 29, 2017 7:04 am

### Bigger or Smaller Acidity Constant in Cations?

Hi

Would you expect Ka (Acidity Constant) of

[Fe(H20)6]^2+

to be bigger or smaller than

[Fe(H20)6]^3+

?

I understand that the iron cation w 3+ has a higher positive charge. What does that tell us about Ka?

Ty!

Curtis Tam 1J
Posts: 105
Joined: Thu Jul 13, 2017 3:00 am

### Re: Bigger or Smaller Acidity Constant in Cations?

Ka would be smaller. The smaller 2+ charge yields less interaction with the oxygen lone pair so the resulting conjugate base would be less stable than that of [Fe(H2O)6]3+