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Topic: Chemical Formula for Potassium Iodide-Iodate  (Read 34551 times)

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Offline Sis290025

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Chemical Formula for Potassium Iodide-Iodate
« on: April 02, 2006, 09:44:46 AM »
What is the chemical formula for a potassium iodide-iodate solution? I know that potassium iodide is KI and potassium iodate is KIO3.

Thank you for any help.

Offline Alberto_Kravina

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #1 on: April 02, 2006, 09:46:20 AM »
Iodide is oxidized to elementar iodine with iodate.

Offline Sis290025

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #2 on: April 02, 2006, 10:05:29 AM »
From that, is this setup even remotely correct?

KI + KIO3 --> I2

(I'm trying to understand the oxidation in this situation. Thanks.)
« Last Edit: April 02, 2006, 10:06:10 AM by Sis290025 »

Offline Alberto_Kravina

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #3 on: April 02, 2006, 10:14:57 AM »
From that, is this setup even remotely correct?

KI + KIO3 --> I2

(I'm trying to understand the oxidation in this situation. Thanks.)
Yeah! Remotely correct! Try to write two half-reactions!

Offline Sis290025

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #4 on: April 02, 2006, 04:02:07 PM »
I am assuming that this solution is in a basic solution and not acidic:

IO3- + I- --> I2

a. Oxidized: IO3- --> I2
b. Reduced: I- --> I2

a. IO3- --> I2
 12OH- + 12H+ + 2IO3- --> I2  + 6H2O
10e- + 12H2O + + 2IO3- --> I2 + 6H2O + 12OH-
10e- + 6H2O + 2IO3- --> I2 + 12OH-

b. I- --> I2
2I- --> I2
2I- --> I2 + 2e-
5(2I- --> I2 + 2e-)= 10I- --> 5I2 +10e-


10e- + 6H2O + 2IO3- --> I2 + 12OH-
10I- --> 5I2 +10e-
__________________________________________
6H2O + 2IO3- + 10I- --> I2 + 12OH- + 5I2 ???




Thanks.
 

« Last Edit: April 02, 2006, 04:28:31 PM by Sis290025 »

Offline Albert

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #5 on: April 02, 2006, 04:07:34 PM »
I am assuming that this solution is in a basic solution and not acidic:

WHY?!

Quote
IO3- --> I2


This reaction takes place in acidic conditions.

Offline Sis290025

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #6 on: April 02, 2006, 04:12:26 PM »
Why does it take place under acidic conditions? I don't understand that part.



Thanks again.

Now that this is the method for a potassium iodide-iodate solution, how do I write the equation for the reaction between this iodide-iodate solution with sulfuric acid, H2SO4?
« Last Edit: April 02, 2006, 04:32:46 PM by Sis290025 »

Offline Albert

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #7 on: April 02, 2006, 04:36:49 PM »
I read your previous post again. The equation WAS balanced also under basic conditions. However, when I performed this very titration, I carried it out under acidic condition. Moreover, it's easier to balance reactions this way.  ;)
« Last Edit: April 02, 2006, 04:43:14 PM by Albert »

Offline Albert

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #8 on: April 02, 2006, 04:52:20 PM »
Now that this is the method for a potassium iodide-iodate solution, how do I write the equation for the reaction between this iodide-iodate solution with sulfuric acid, H2SO4?

I think it's just potassium iodide which reacts with sulfuric acid.

Offline Borek

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #9 on: April 02, 2006, 05:12:41 PM »
Oxyacids oxidation potential is higher in low pH, that's whay they are used in solutions of strong acids. Cl- gets easily oxidized to Cl2, so sulfuric acid is preferred over hydrochloric for solution acidification.
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Offline Sis290025

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #10 on: April 02, 2006, 06:22:08 PM »
Basically, I'm trying to find the molarity of a titrant sodium thiosulfate solution (containing NaOH and Na2S2O3) through standardization in which a mixture of H2SO4 and the potassium iodide-iodate solution, along with starch indicator, are involved.

The setup of equations is giving some difficulty. Can anyone direct me, or give me hints, on how to write out the equations involved, so I can eventually find the molarity?

Thanks for any help.
« Last Edit: April 02, 2006, 06:22:57 PM by Sis290025 »

Offline Borek

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #11 on: April 02, 2006, 06:42:48 PM »
IO3- + I- + H+ -> I2 + H2O

I2 + S2O32- -> I- + S4O62-

Note these are not balanced.
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Offline Sis290025

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #12 on: April 02, 2006, 06:56:05 PM »
To balance them, how can I tell if it is a basic or an acidic condition?

To find the molarity, I would use the ratio of mol of IO3- to mol S2O3(2+)?

 
« Last Edit: April 02, 2006, 06:57:48 PM by Sis290025 »

Offline Borek

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #13 on: April 02, 2006, 07:05:09 PM »
Both go in low pH, but it doesn't matter, just balance them.

Amount od iodine produced is defined by mass of iodate used, rest is simple stoichiometry.
« Last Edit: April 02, 2006, 07:07:13 PM by Borek »
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Offline Sis290025

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #14 on: April 02, 2006, 08:16:24 PM »
For second part,

I2 --> 2I-
2e- + I2 --> 2I-

2S2O3(2-) --> S4O6(2-) + 2e-
2e- + I2 --> 2I-
________________________________
2S2O3(2-) + I2 --> 2I- + S4O6(2-)

First part:
using change-in-oxidation method-

IO3- + 5I- +6H+ --> 3I2 + 3H2O ???


« Last Edit: April 02, 2006, 08:41:14 PM by Sis290025 »

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