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Topic: Qualitative Lab Help [AP CHEM]  (Read 2074 times)

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Offline frendmatt

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Qualitative Lab Help [AP CHEM]
« on: May 10, 2016, 02:23:34 PM »
Our teacher gave each student a set of solutions to which we need to use to figure out the others. We have access to 1M HCl and 1M NaOH and pH paper

My solutions are:
AgNO3
Cu(NO3)2
HCl
Pb(NO3)2
NaC2H3O2
NaI

None of the solutions are labeled, and he deducts 5 points for each incorrect guess and does not tell which ones you got right. I can easily identify the copper solution and the remaining Nitrates through adding HCL (atleast i believe this would work) but conflicting solubility rules on the internet are stumping me. Can anyone help me a bit with a procedure or at least solubility rules for this lab? Thank you.

Offline AWK

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Re: Qualitative Lab Help [AP CHEM]
« Reply #1 on: May 10, 2016, 02:35:36 PM »
Two solution you can identify using pH paper.
Other three with NaOH solution.
The last one can be identified mixing separately with above three solutions.
In most cases color is more important than solubility.
AWK

Offline frendmatt

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Re: Qualitative Lab Help [AP CHEM]
« Reply #2 on: May 10, 2016, 02:40:41 PM »
Two solution you can identify using pH paper.
Other three with NaOH solution.
The last one can be identified mixing separately with above three solutions.
In most cases color is more important than solubility.
Okay, for pH paper im assuming it will be HCl andThe NaC2H3O2, HCL will be around 1 and acetate may be low pH EDIT: High pH?
I know Cu can be identified with OH but what else? Ag and Pb?
And for the colors of the solutions, one is blue (Copper) but the other is a sort of yellow almost like urine, but i cant for the life of me find any information on what that could be
« Last Edit: May 10, 2016, 02:58:50 PM by frendmatt »

Offline frendmatt

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Re: Qualitative Lab Help [AP CHEM]
« Reply #3 on: May 10, 2016, 03:36:57 PM »
New thought, im thinking the OH will precipitate with the Ag, CU, Pb, ill tell CU by color then ill use pH to test HCl and NaI, then the acetate will need to be used with the nitrates to determine the different nitrates.

Offline AWK

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Re: Qualitative Lab Help [AP CHEM]
« Reply #4 on: May 10, 2016, 03:49:19 PM »
I meant colour also after reaction.
Quote
Ag and Pb?
Also with NaOH - colour for the former, colour and dissolution in an excess of reagent for the later.
Quote
but the other is a sort of yellow almost like urine
This concerns the last solution - this solution forms colour solution and/or precipitates with Cu2+(redox reaction), Pb2+ and Ag+.

Note - in all cases you should write down correct and balanced reactions (probably) except for pH test.
The first thought concerning sodium acetate was correct.
AWK

Offline frendmatt

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Re: Qualitative Lab Help [AP CHEM]
« Reply #5 on: May 10, 2016, 04:01:06 PM »
Ok thank you so much, i just wrote up a good procedure and ill be able to test it thursday! :)

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