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Topic: volumetric analysis  (Read 2623 times)

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Offline yungyee

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volumetric analysis
« on: November 11, 2013, 02:16:35 AM »
anyone can teach me how to do about my project
it's been so long i thinking of it
but still dont have any idea how to solve the question given

KA1 is 0.050 moldm-3 aqueous iodine
KA2 is 0.100moldm-3 aqueous sodium thiosulphate
KA3 is a solution containing 24.00g of anhydrous sodium sulphite,Na2SO3,per dm3
KA4 is 2g sodium hydrogencarbonate
starch is used as an indicator

1.pipette 50cm3 of KA1 into titration flask
2.add 25cm3 of KA3 slowly into the titrations flask containing KA3 by using another pipette and shake
3.add 2g of KA4 and shake the flask again
4.titrate the resulting solution with KA2 using starch as indicator

calculate the volume of I2 that did not reacted with the sulphite ions

Can anyone teach me to solve it...

Offline Archer

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Re: volumetric analysis
« Reply #1 on: November 11, 2013, 02:38:56 AM »
Write a balanced equation for this reaction first, this will help.

Also provide your titration results.
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Offline yungyee

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Re: volumetric analysis
« Reply #2 on: November 11, 2013, 03:18:31 AM »
50cm3 of KA1 required 26.2cm3 of KA2 for a complete reaction

and then my balance equation for the reaction between iodine and the thiosulphate ion

2S2O32- + I2 = S4O62- + 2I-

the balance eq for the I2 and sulphite ions im nt sure ><
is it  I2 + SO32- = 2I- + ???
confuse @@




Offline Borek

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Re: volumetric analysis
« Reply #3 on: November 11, 2013, 03:57:15 AM »
Sulfite gets oxidized to sulfate. Balance O/H with water and H+.
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