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Topic: Redox reaction  (Read 325 times)

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Offline Glitch000

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Redox reaction
« on: November 10, 2021, 02:55:44 PM »
hi, can someone help me balance this redox reaction please?

ClO3- + As2S3 > Cl- + H2AsO4- + SO42-

Thank you

Online Borek

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Re: Redox reaction
« Reply #1 on: November 10, 2021, 03:13:24 PM »
What have you tried so far?

Do you want to use oxidation number method, or half reaction method?
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Offline Glitch000

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Re: Redox reaction
« Reply #2 on: November 10, 2021, 03:26:28 PM »
first of all i found the oxidation number of the single atoms:

reagents:
Cl = +V
As2= +III
S3= -II

products:
Cl-= -I
As= +V
S= +VI

Then i wrote the half-reaction of oxidation and reduction:

ox: As23+ > 2AsO43- + 4e-

is this right? i don't know how to continue the balance of this half-reaction... now i have to balance the charge right?
the reaction is in an acid solution

« Last Edit: November 10, 2021, 05:33:50 PM by Glitch000 »

Offline Glitch000

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Re: Redox reaction
« Reply #3 on: November 10, 2021, 03:42:16 PM »
I've also done the other half-reaction btw...

Ox: 14H2O + S32- > 3SO42- + 24e- + 28H+

Red: 6H+ + 6e- + ClO3- > Cl- + 3H2O

Is this correct?
« Last Edit: November 10, 2021, 05:19:34 PM by Glitch000 »

Offline mjc123

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Re: Redox reaction
« Reply #4 on: November 10, 2021, 05:37:19 PM »
Don't write As23+. That looks like something with 2 As atoms and a charge of 3+, i.e. an average oxidation number of 1.5. That's not what you mean (I hope). It will lead to confusion in balancing the charges. Write 2As3+. Likewise S32- (this is a species that actually exists, so it is important not to get confused with it). You mean 3S2-. Your equation is unbalanced as regards charge, H and O.

Offline Glitch000

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Re: Redox reaction
« Reply #5 on: November 10, 2021, 06:00:51 PM »
Oh you're right, my bad! i meant 2As3+ and 3S2-...

May i ask you a question... since there is the 2 as a stoichiometric coefficient in
 2As3+ > 2AsO43- + 4e-
i have to multiply by 2 also H+ and H2O?
And also, to balance the charge, i have to consider the stoichiometric coefficient? i mean, the total charge of the products is -10 ( since 2As3- has a total charge of -6 ( i multiplied -3 x 2) and then 4e-) or -6?
and the same for the reagent... (2As3+) is it +3 or +6?
sorry for my bad explanation, i'm not very good in english haha, hope you understand
« Last Edit: November 10, 2021, 06:11:46 PM by Glitch000 »

Offline mjc123

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Re: Redox reaction
« Reply #6 on: November 11, 2021, 05:27:20 AM »
You need the right number of H+ and H2O to balance the equation. You also have to balance the charges, and yes you have to consider the stoichiometric coefficient. (What do you think it means?) So your equation as written has +6 on the left and -10 on the right.

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