Stoichiometry

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Dhamnekar Winod
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Stoichiometry

Post by Dhamnekar Winod »

The antiseptic tincture of iodine is a solution of iodine and KI in ethyl alcohol(CH3CH2OH). When a sample of tincture of iodine weighing 5.000 g is diluted with water and titrated with 0.1500 M Na2S2O3 solution, 19.75 mL of the latter is required. The reaction is

I2 + 2 Na2S2O3 → 2NaI + Na2S4O6

What is the weight percentage of I2 in the sample?

My answer: 19.75 mL of Na2S2O3 is 0.0029625 mol of Na2S2O3. So it requires 0.00148125 mol of I2. Molar mass of I2 =253.8 g.

So, we get 0.37594125 g per 5.000 g of sample of tincture of iodine. So, the weight percentage of I2 in the sample is 7.519 %
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ChenBeier
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Re: Stoichiometry

Post by ChenBeier »

Correct if the free I2 is meant. As described its a solution of I2 and KI what means KI3, then the iodine of the salt is missing.
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Dhamnekar Winod
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Re: Stoichiometry

Post by Dhamnekar Winod »

A solution of iodine and KI in ethyl alcohol means what. Would you give me examples of iodine of salt?
Last edited by Dhamnekar Winod on Sun Mar 27, 2022 8:02 am, edited 1 time in total.
Any science consists of the following process. 1) See 2)Hear 3)Smell,if needed 4)Taste, if needed 5)Think 6)Understand 7)Inference 8)Take decision [Believe or disbelieve, useful or useless, true or false, cause or effect, any other criteria]
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ChenBeier
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Re: Stoichiometry

Post by ChenBeier »

Here we have potassium triiodide

https://pubchem.ncbi.nlm.nih.gov/compou ... onohydrate

It is made by iodine and potassium iodide.

The whole compound is dissolved in alcohol.
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