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Topic: Yellow color in HCl?  (Read 10768 times)

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Offline Theoden

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Yellow color in HCl?
« on: January 31, 2017, 06:50:24 PM »
     Hi, I have just made a solution of hydrochloric acid by running the current of three D batteries through an aqueous solution of NaCl, thus isolating the Cl-:spinup:, which hydrated the water ( Cl- + 2H2:rarrow: H3O- + Cl- + H + O ).
     But the solution is now an opaque yellow. Is this the result of an impurity? I have researched this for a while only to receive that possibility, as well as the possibility that my HCl(aq) might have "oxidated". Are these valid proposals?

     Thanks in advance!

Offline Arkcon

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Re: Yellow color in HCl?
« Reply #1 on: January 31, 2017, 08:00:13 PM »
     Hi, I have just made a solution of hydrochloric acid

Awesome

Quote
by running the current of three D batteries through an aqueous solution of NaCl, thus isolating the Cl-:spinup:, which hydrated the water ( Cl- + 2H2:rarrow: H3O- + Cl- + H + O ).

Nope, you didn't.  Those reactions don't happen, and you've forgotten other ions, which prevent it from happening.

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     But the solution is now an opaque yellow. Is this the result of an impurity?

Very likely.  Or more likely mostly impurity, and no HCl.

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I have researched this for a while only to receive that possibility, as well as the possibility that my HCl(aq) might have "oxidated". Are these valid proposals?

There are others.  You can find out what you'll get from NaCl solution electrolysis.  You can even search our forum.

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     Thanks in advance!
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline Theoden

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Re: Yellow color in HCl?
« Reply #2 on: January 31, 2017, 09:49:28 PM »
Thanks! Your answer may have been a little disappointing, but I'm glad someone responded.
Only, do you have an idea on what the yellow coloring might indicate?

Offline billnotgatez

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Re: Yellow color in HCl?
« Reply #3 on: January 31, 2017, 10:06:17 PM »
@Theoden

https://en.wikipedia.org/wiki/Chloralkali_process

Read this and come back with your thoughts

Offline Theoden

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Re: Yellow color in HCl?
« Reply #4 on: January 31, 2017, 10:44:09 PM »
@Theoden

https://en.wikipedia.org/wiki/Chloralkali_process

Read this and come back with your thoughts

Is it possible I may have sodium hypochlorite? I didn't use an ion-permeable membrane for my experiment, so I could have some ClO3- ions swimming around in there. If I am correct, many solutions of NaClO3 are a yellowish hue.

Offline billnotgatez

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Re: Yellow color in HCl?
« Reply #5 on: January 31, 2017, 10:46:22 PM »
That would be my guess too

Offline Borek

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Re: Yellow color in HCl?
« Reply #6 on: February 01, 2017, 02:10:05 AM »
In most cases impurities come from the electrodes used. All compounds listed so far are not yellow when pure (white as solids, colorless in the solution).
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Offline AWK

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Re: Yellow color in HCl?
« Reply #7 on: February 01, 2017, 04:05:44 AM »
My guess - iron electrodes
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Offline Borek

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Re: Yellow color in HCl?
« Reply #8 on: February 01, 2017, 06:14:34 AM »
Binding from the graphite often gives a yellow tint as well.
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Offline Theoden

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Re: Yellow color in HCl?
« Reply #9 on: February 01, 2017, 08:49:00 AM »
My guess - iron electrodes
I looked up FeCO3 and found that it was, in fact, a yellowish hue; but I was actually using copper electrodes. However, I don't completely doubt these electrodes had something to do with the reaction.

Binding from the graphite often gives a yellow tint as well.
I'm afraid I didn't have any carbon in my experiment, even for the electrodes. I've had a shortage in zinc-carbon batteries, so I had to just use plain copper. Once, when I did use carbon electrodes, I had a CuCO3 precipitate developing from the connection between the graphite and copper wire. Only, it was a light blue rather than yellow, and settled at the bottom of the container.

Offline Borek

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Re: Yellow color in HCl?
« Reply #10 on: February 01, 2017, 09:39:27 AM »
I'm afraid I didn't have any carbon in my experiment, even for the electrodes.

You didn't gave any details, so we had to wild guess.
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Offline Theoden

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Re: Yellow color in HCl?
« Reply #11 on: February 01, 2017, 06:39:45 PM »
I'm afraid I didn't have any carbon in my experiment, even for the electrodes.

You didn't gave any details, so we had to wild guess.
I apologize for my failure to provide that information; at the time it didn't cross my mind that such would be needed. Here is a list of everything I used:
-Borosilicate glass apparatus
-3 D-batteries
-Insulated copper wire
-Distilled H2O
-NaCl

Offline AWK

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Re: Yellow color in HCl?
« Reply #12 on: February 01, 2017, 07:02:22 PM »
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-Insulated copper wire

???
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Offline Borek

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Re: Yellow color in HCl?
« Reply #13 on: February 02, 2017, 03:39:30 AM »
Insulated copper wire

You mean only the final part, stripped of insulation, was in contact with water?

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-NaCl

Purity?

Still, even with all the details (and thank's for giving them, they are always an important part of the problem) the only viable answer is a rather vague "impurities". As I wrote earlier, all salts and compounds produced (apart from possible copper compounds) are colorless (and yellow is not a typical color of copper compounds).
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Offline skilpadderr

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Re: Yellow color in HCl?
« Reply #14 on: February 02, 2017, 07:14:33 AM »
i'm definitely not a chemist but i will try to help;

what voltage did you applied? this is really important because with an high voltage ( i think more than 14V) i'm quite sure you get almost only a brown/orange Cu2O precipitate,

with lower voltages, i'm not sure about what can happen but i think you get a mixture of Cu(OH)2 maybe small amounts of CuCl, CuCl2? and a little of chlorine gas can be produced at the anode leaving NaOH in solution.

i think that a mixture of this compounds can give a dirty greenish yellow colour but Cu(OH)2 and Cu2O will soon settle to the bottom leaving the water clear...

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