[remcalis]

I have the infamous "Test Tube Mystery" lab practical coming up next week. The twelve solutions that will be provided are:

6M HCl
0.1M Cu(NO3)2
0.1M NiCl2
3M H2SO4
0.1M Ba(NO3)2
0.1M FeCl3
6M NH4OH
0.1M AgNO3
0.1M K2CrO4
6M NaOH
0.1M Pb(NO3)2
0.1M Na2CO3

I am not allowed any litmus paper or any additional chemicals. What is the best strategy for these particular chemicals? I should be able to get these ones right off the bat:
Cu(NO3)2: blue
K2CrO4: yellow
NiCl2: green
FeCl3: orange
NH4OH: smells strongly

After that, I plan to mix K2CrO4 with the remaining chemicals. Ag(NO3) should give me a blood red precipitate.  Only two other solutions should produce a precipitate:
Pb(NO3)2 and Ba(NO3)2. 

They both produce a yellow precipitate.  I could then test them both with the ammonia, as the Pb(NO3)2 should produce a white precipitate, and the Ba(NO3)2 should produce no precipitate.  Is that last part correct?

If that whole strategy works, I should be left with only HCl, NaOH, H2SO4, and Na2CO3.


What is the best strategy from this point on? 


Thanks so much!

[Borek]

What happens to silver in the presence of chlorides?

What happens to carbonates in the presence of acids?

[remcalis]

Silver precipitates in the presence of chlorides (white ppt).  But it also precipitates in the presence of OH (brown ppt) and CO3 (brownish/white ppt). 

Carbonates bubble in the presence of acids, but will it still bubble noticeably even though its only 0.1 M Na2CO3?

So, if I mix silver with the remaining solutions, I will get:
Na2CO3 (brownish/white ppt)
H2SO4 (no ppt)
HCl (white ppt)
NaOH (brown ppt)

That way, I could determine which one was H2SO4.  The other three might be a little harder to tell.  HCl would probably be the easiest to see since it is plain white.  From there, I could mix the three solutions into the H2SO4, and whichever one bubbled would be Na2CO3.  Then I would be left with HCl and NaOH.  I would mix these together, checking for heat to confirm that they are in fact an acid/base.  Then I could mix the Na2CO3 into them both, and whichever one bubbled would be HCl. 

From there, I would want to do some confirmatory testing.

What are some other good tests I could use to determine Ba(NO3)2, Pb(NO3)2, HCl, H2SO4, NaOH and Na2CO3?

[Borek]

What other precipitates can you think of?