[recklesskelly]

I've got a typical 10 test tube mystery in my chemistry lab. We have 10 unknowns and are only allowed to use the solutions, water, a dropper, and a watch glass to put the chemicals on for reactions. No pH testing or extra chemicals allowed. My chemicals are:
H2SO4, HCL, NH3, NaOH, Pb(NO3)2, SnCl4 in HCL, Cr(NO3)3, BiCl3 in HCl, Mg(NO3)2, and Fe(NO3)3.
I've got an idea on a few of these but desperately need any help you can give me. Thanks!

[wereworm73]

So which ones were giving you trouble?

[recklesskelly]

Mainly the SnCl4 and the BiCl3 solutions.

[wereworm73]

Normally, the presence of bismuth is tested with stannous chloride (SnCl₂), which reduces the bismuth ions to bismuth metal (appearing as a black powder).  I'm not sure if that's an option in your case, but you can tell it apart from SnCl₄ by using NaOH.  You'll get a Bi(OH)₃ precipitate which does NOT dissolve in excess NaOH.  SnCl₄, on the other hand, forms Sn(OH)₄ under mildly basic conditions but adding excess NaOH dissolves this Sn(OH)₄ to form the soluble Sn(OH)₆^2-.

[recklesskelly]

Does the Mg(NO3)3 react with either the SnCl4 or the BiCl3?

[wereworm73]

No, but it also forms a precipitate in NaOH.  But it's noticably more gel-like than Bi(OH)₃ or Sn(OH)₄.

[Alberto_Kravina]

My favourite test for Bi: Add KI solution ?black ppt. soluble in excess KI as potassiumtetratiodobismutate(III)

Bi³⁺ + 3I^- ? BI₃ (Black ppt.)
BI₃ + I^- ? [BiI₄]^- (Deep-red complex)