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Topic: Chemical Formula for Potassium Iodide-Iodate  (Read 34566 times)

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Offline Borek

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #15 on: April 03, 2006, 03:29:45 AM »
Both OK :)
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Offline Sis290025

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #16 on: April 03, 2006, 06:45:51 AM »
Now that the equations are balanced, I am still unsure of how to use the stoichiometry since there are two separate equations  :-[. How do I connect them?

Thanks again.
« Last Edit: April 03, 2006, 06:48:26 AM by Sis290025 »

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #17 on: April 03, 2006, 08:11:32 AM »
You should know mass of iodate used - use it to calculate how much iodine was produced in the first reaction. This is the amount used in the second part.
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Offline Sis290025

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #18 on: April 03, 2006, 02:20:36 PM »
An already prepared 0.00125 M potassium iodide-iodate solution was used. Does this mean that the mass is 0.00125 mol of iodate to start off?

Thanks again.
« Last Edit: April 03, 2006, 02:22:20 PM by Sis290025 »

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #19 on: April 03, 2006, 02:38:17 PM »
n=CV

Is it 0.00125 iodide, 0.00125 iodate, or both? Usually iodide is used in small excess.
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Offline Sis290025

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #20 on: April 03, 2006, 03:00:46 PM »
Well, I suppose it is both since the chemical bottle is labelled potassium iodide-iodate, but I don't know how many grams of iodate or iodide was used to create the solution's molarity.
« Last Edit: April 03, 2006, 03:01:53 PM by Sis290025 »

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #21 on: April 03, 2006, 03:27:34 PM »
I think you should assume it is 0.00125 in both. atlhough that's probably not true. Still, n=CV holds.
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Offline Sis290025

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #22 on: April 03, 2006, 09:04:25 PM »
So to find the more accurate number of moles, I would let

n = 0.00125 M*.2 L of iodide-iodate solution used = mol of IO3- instead of mol IO3- = 0.00125 M?

Then, mol of IO3-(3 mol I2/1 mol IO3-)*(2 mol S2O3 (2-)/1mol I2) = mol of  S2O3 (2-)

M of sodium thiosulfate = mol of  S2O3 (2-)/ L of titrant used

Thanks again.
« Last Edit: April 03, 2006, 09:07:03 PM by Sis290025 »

Offline Sis290025

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #23 on: April 04, 2006, 11:44:49 AM »
Is the above method correct?

Any help is greatly appreciated.

Offline Borek

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #24 on: April 04, 2006, 11:49:02 AM »
Seems OK. Where did you get 0.2L from - I don't recall this value posted earlier. Is it the volume of the iodide/iodate solution used?
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Offline Sis290025

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Re:Chemical Formula for Potassium Iodide-Iodate
« Reply #25 on: April 04, 2006, 12:22:21 PM »
Yes, 200 mL of the solution was used. As a matter of fact, it was 20 mL of 0.0125 M of potassium iodide-iodate solution plus 180 mL of H2O to create 0.00125 M of potassium iodide-iodate . . .  

Offline Sis290025

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Re: Chemical Formula for Potassium Iodide-Iodate
« Reply #26 on: April 12, 2006, 05:26:33 AM »
Quote
IO3- + I- + H+ -> I2 + H2O

I2 + S2O32- -> I- + S4O62-

Note these are not balanced.


How did you setup, or get, these equations?

Thanks again.

Offline Borek

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Re: Chemical Formula for Potassium Iodide-Iodate
« Reply #27 on: April 12, 2006, 05:43:43 AM »
They are published in most analytical chemistry books, they can be also googled in less then 30 seconds.
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