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Saturation of a salt

1. What is the saturated [Al3+] concentration at pH7 made by the addition of AlCl3 to distilled water?

2. AlCl3<-->Al3++3Cl-
3H2O<-->3H++3OH- Kw=1x10-14
Al3++3OH-<-->Al(OH)3 Ksp=3x10-34

3. I'm familiar with this type of problem, but not the way in which it's being asked. I hope I have included the equations and constants that are pertinent below. I would start by taking the Ksp for the precipitate and mulitplying it by 1/Kw. This multiplied by the solubility product for AlCl3 should give the equilibrium product for the whole equation, but I don't know how to get that.


Unfortunately question is ambiguous. It is not entirely clear to me it if should be read as "you add AlCl3 to distilled water at pH 7.0, what is the resulting [Al3+]" or "you added AlCl3 to distilled water and you fund pH to be 7.0, what is [Al3+]". These are different problems.

I guess it has to be read the second way. If so... what is concentration of OH-?
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