asdfqazx - 10-12-2008 at 20:05
Hi,
Does any body have information about the hydrolysis of CaCl2, MgCl2 and NH4Cl. Any curve, figure for equilibrium constant, calculating the PH for
various concentration, etc will be appreciated.
kclo4 - 10-12-2008 at 21:38
Perhaps you mean dissolution, or ionization?
Hydrolysis is generally, or perhaps always the breaking apart of a molecule with the addition of water.
Lewis Acids do it. Aluminum chloride is an example of such. AlCl3 + 3 H2O = Al(OH)3 + 3HCl
Perhaps Wikipedia would be of use, looking to dissolution, ionization, hydrolysis, dehydration, precipitation, etc seems like they would be very
useful to you.
Also, I realize this is your first post, but it helps if you put more information into the question so we know exactly what it is you are looking for.
Also, with simple questions like this, it would be good to post these in the Short Question Thread, or the begging section.
kilowatt - 10-12-2008 at 22:21
That same thing happens when you heat or dissolve hydrated MgCl2 or CaCl2, for example CaCl2*2H2O --> Ca(OH)2 + 2HCl. That may be what he is
asking about. I wish I know the answer as it is very pertinent to my latest endeavors.
[Edited on 10-12-2008 by kilowatt]
kclo4 - 11-12-2008 at 15:13
Well NH4Cl and CaCl2 aren't going to hydrolyze, unless I'm missing something, and MgCl2 is only going to go to Mg(OH)Cl + HCl isn't it?
kilowatt - 12-12-2008 at 06:31
If you think CaCl2 wouldn't hydrolyze I guess you haven't fused any CaCl2 hydrates before. It does release plenty of HCl if done under normal
conditions. I don't know about under vacuum or more gradual or controlled heating though, and it probably is just to Ca(OH)Cl like with Mg, but the
system containing that can still be written in terms of CaCl2, CaO, HCl, and H2O.
NH4Cl simply decomposes to form NH3 and HCl when sublimed, in equilibrium anyhow.
I suspect asdfqazx is asking about the hydrolysis upon dissolution though. You can calculate this by measuring the pH of a solution of known
molarity. The equilibrium constant is the molarity of H+ over the molarity of the reagent. Then you can calculate the pH for other concentrations.
[Edited on 12-12-2008 by kilowatt]