attempting to prepare some alcl3 i thought, 'oh, i'll just dissolve some al in hcl and the alcl3 will be right there for tha evappin' so, sheet after sheet of shiny foil bubbled and blackened it's way into the brew, but something was amiss. after inhaling way too much hydrogen that seemed to burn like it had never done before, i went to THE BOOK and was humbled. alcl3 reacts violently with water to produce hcl. further reading lead me to believe the al would now be floating around the clear solution as [Al(H2O)6]3+, which equilibrilises to [Al(H2O)6]3+ <=> 3H+ + Al(H2O)3(OH)3(s)...being in the mood for something concrete to salvage (even if it wasn't my beloved alcl3) i said, heck i might just precipitate the darn thing and be done with it. add a weak base, methinks, so i start bubbling CO2 through the crystal clear solution. after about 6 moles of CO2 my solution is still precipitatless, but my hand is burning where i was holding the tube in. my co2 pump was just some bicarb(aq) splashed with a little conc. H2SO4...oh no...could some SO2 have evolved, evapped, along with it? what WAS the mystery acid? i didn't care until i dried the shit out, but more on that in a second.
so i thought fuck it, i'll just add Na+ ions, and neutralised the al solutions with a few BIG pinches of bicarb. a cruddy white precipitate was suspended around and i thought great it's my Al(H2O)3(OH)3. so i boiled the stuff down with stirring (as there was insufficient crud to filter) came back to find my stir bar poised in green goo.
green? okay. washed twice with acetone which carried the green-yellow goo away leaving white gelatinous sand like crystals. spread them out to dry. although the co-ordinated waters weren't going to leave so the stuff would stay wettish, that i expected. what i didn't expect was that on exposure to air the shit goes yellow. all of it. bright flourescent sumblimed sulfur yellow!!! wtf? there's no free sulfur there cause it dissolved clear. acetones *cleans* it but then it returns. what al compound is yellow?!!?!
any ideas?