[fusi0n556]

please help..  I got a few of them but not all of them, please can some one write me a method!!!!


8 Unknown substances labeled A,B,C,D,E,F,G,H

these unknown substances are:
0.1M Aluminum nitrate
Ethanol
0.1M Hydrochloric acid
0.1M Sulfuric acid
0.1M Zinc nitrate
0.1M Lead nitrate
0.1M Sodium iodide
propanone

i have to identify each label to one of these unknown substances


WHAT I AM ALLOWED:
0.1M NaOH
0.1M HCl
0.1M AgNO3
0.1M BaCl2
Acidified 0.1M K2Cr2O7
2.0M Ammonium hydroxide (ammonia) solution
Universal indicator
pH color chart
Red/Blue litmus paper
Tweezers
Wax taper
Distilled water
other common laboratory equipment... test tube/rack, Bunsen burner



PLEASE WRITE ME A METHOD ON HOW I COULD LABEL THE UNKNOWN SUBSTANCES

[Borek]

Please read forum rules. Show what you already did.

[fusi0n556]

the thing is that what i have already done might not be right.... but this is what ive done

test all of them with blue/red litmus paper

blue -> red means that i got H2SO4, HCl

from there i reacted with NaOH and then used universal indicator to find Na2SO4 acidic

nothing on the nitrates, or the sodium iodide

Ethanol will oxidise with K2Cr2O7 but propanone will not oxidise (but i dont know what to observe to see this)   

i hope that is right??

[Borek]

pH idea is a good one to find acids.

Not sure what you mean by

from there i reacted with NaOH and then used universal indicator to find Na2SO4 acidic

it doesn't make any chemical sense to me.

Check solubilities table, it should give you further hints.

For example - you have already identified two acids - HCl and H₂SO₄. What will happen if you add BaCl₂ to each?

Note that once you have identified one of the solutions, you can use it as a reagent.

[fusi0n556]

well please tell me if im wrong but i thought

H2SO4 + NaOH -> Na2SO4 (which is acidic salt) + H2O

HCl + NaOH > NaCl (nuetral) + H2O
 

[Astrokel]

well please tell me if im wrong but i thought

H2SO4 + NaOH -> Na2SO4 (which is acidic salt) + H2O

HCl + NaOH > NaCl (nuetral) + H2O
 

not really, Na₂SO₄ is a basic salt due to the sulphate ion.

SO_4^2- + H₂O ---> HSO₄^- + OH^-

What will happen if you add BaCl2 to each?

Check out this hint given by Borek

Ethanol will oxidise with K2Cr2O7 but propanone will not oxidise (but i dont know what to observe to see this)

Yes propanone cannot be oxidized by potassium dichromate, dichromate ion will be reduced to Cr³⁺ and the colour change is?

[Borek]

H2SO4 + NaOH -> Na2SO4 (which is acidic salt) + H2O

HCl + NaOH > NaCl (nuetral) + H2O

First of all, as Astrokel already pointed out, sodium sulfate pH will be slightly basic (very slightly) due to the fact that second proton in sulfuric acid is not that strong acid as the first one. However, there is much more important error in your thinking. Final pH of these solutions will not depend on the salt produced, but on the amunt of base added. This is not the same as dissolving salt, when final pH depends on teh salt properties. This is solution in which reaction with limiting reagents occur. Too much base and pH will be high, not enough base and pH will be low. Final pH doesn't give any information about the original subtance.

[fusi0n556]

well can u tell me how u wud do it then?

[Borek]

I gave you several hints almost 24h ago.