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November 01, 2025, 12:48:30 pm
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Author Topic: Brine  (Read 1213 times)  Share 

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StringFever

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Brine
« on: November 11, 2009, 10:22:48 am »
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Just quick question:

Is it meant to be assumed knowledge that brine is heavily concentrated NaCl and that if used in electrolysis, it would bump Cl2/Cl- below water so that it becomes a stronger reductant than water?
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rajah21

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Re: Brine
« Reply #1 on: November 11, 2009, 10:31:18 am »
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Yeah my teacher said that it's handy to remember just in case the exam doesn't explicitly state the brine is highly concentrated etc etc
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Hooligan

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Re: Brine
« Reply #2 on: November 11, 2009, 10:36:13 am »
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Quote from: StringFever on November 11, 2009, 10:22:48 am
Just quick question:

Is it meant to be assumed knowledge that brine is heavily concentrated NaCl and that if used in electrolysis, it would bump Cl2/Cl- below water so that it becomes a stronger reductant than water?

Yup! ^_^

I always remember:
1. High conc. of Cl- = Cl- reacts
2. Low conc. of Cl- = water reacts

... and Cl- reacts when there are high concs of it, because the electrochemical series table is only for standard conditions, and obviously when we have high concs of Cl- (>0.1M) we're not at standard conditions, thus causing its reaction over water. :)
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c23

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Re: Brine
« Reply #3 on: November 11, 2009, 10:37:29 am »
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yup

under difference conditions, the ESC order changes
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StringFever

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Re: Brine
« Reply #4 on: November 11, 2009, 10:42:30 am »
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Thanks everyone! :)
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simpak

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Re: Brine
« Reply #5 on: November 11, 2009, 11:59:22 am »
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I hate it when this happens, I always forget and choose water.
But, extra question, when that happens is it correct that there is both the oxidation of water and the oxidation of Cl-?
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Hooligan

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Re: Brine
« Reply #6 on: November 11, 2009, 12:19:39 pm »
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Quote from: mavisgibbons on November 11, 2009, 11:59:22 am
I hate it when this happens, I always forget and choose water.
But, extra question, when that happens is it correct that there is both the oxidation of water and the oxidation of Cl-?

No, just oxidation of Cl-. Oxidation of water only occurs when there is a low conc of Cl-. :)
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simpak

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Re: Brine
« Reply #7 on: November 11, 2009, 01:19:27 pm »
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Quote from: Hooligan on November 11, 2009, 12:19:39 pm
Quote from: mavisgibbons on November 11, 2009, 11:59:22 am
I hate it when this happens, I always forget and choose water.
But, extra question, when that happens is it correct that there is both the oxidation of water and the oxidation of Cl-?

No, just oxidation of Cl-. Oxidation of water only occurs when there is a low conc of Cl-. :)

Y, but experimentally, when there is a concentration of eg 2.0 M in a solution containing Cl-, then the pH decreases and Cl2 is formed...
I did it during my final SAC.
But safer just to stick with only Cl2 being produced if they ask what is being produced at the anode?
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dani

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Re: Brine
« Reply #8 on: November 11, 2009, 03:26:57 pm »
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my teacher said that downs cell and the brine stuff is not in the course anymore

is that true?
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StringFever

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Re: Brine
« Reply #9 on: November 11, 2009, 03:27:34 pm »
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Quote from: dani on November 11, 2009, 03:26:57 pm
my teacher said that downs cell and the brine stuff is not in the course anymore

is that true?

They are examinable.
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