[Dirudel]

Hi all,

I have a question about titration using strong acids and bases in titrations when those strong acids/bases are not monoprotic/monohydroxy.

For example, the Kb2 of Sulfuric acid is finite, meaning the second proton needs just a little coaxing to come out. This means that when you titrate a strong base with H2(SO)4, the final pH is not expected to be 7.0. It is expected to be 7.1 or 7.2 or so.

I've been trying to track down which diprotic and dihydroxy bases exhibit this behavior, and it is difficult because Ka2 and Kb2 values are hard to find for strong acids/bases.

I think I found one reference that suggests Ba(OH)2 has essentially an infinite Kb2, so when one titrates with it, you should still expect a pH of 7.0.

Can someone point me to a reference showing Kb2 values for strong bases?

I'm particularly interested in Ca(OH)2 and Sr(OH)2. I'm trying to find out if they act like Sulfuric acid (Having a very slight problem giving up their second ion, leading to a slight elevation in pH after titration is complete) or if they act like I think Ba(OH)2 acts (Having essentially infinite Kb2, leading to a pH of 7.0).

Thanks!

[Borek]

Don't look for Kb values, look for stability constants of Me/OH complexes. See fourth question here.

[Dirudel]

Thanks!