Taslem
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Chemical reaction?
I was making iodine the HCl, alkali metal iodide way using .1mol solutions and 3% H2O2. It gave a very dilute iodine solution. When I heated it, it
turned clear and looked no different from when I first added the HCl and KI. Does anyone know what happened to the iodine?
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neptunium
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it got disolved....let it cool and add more peroxide..the reaction is exothermic so keep it slow and cool...by the end of it you should be left with a
clear solution with a precipitate of I2
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weiming1998
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It also might have sublimed. Iodine is very easy to sublime, so be careful when heating. If you notice a faintly purple vapour, then it is subliming.
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neptunium
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if you heat it too much it could very much have sublimed very true!
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AJKOER
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OK, the reaction from start to end and the future:
HCl + KI --> KCl + HI
2 HI + H2O2 --> I2 + 2 H2O
Now, Iodine slowly reacts with water. However, with boiling the reaction proceeds:
I2 + H2O <---> HI + HIO
and very rapidly a disproportionation reaction:
3 HIO --> 2 HI + HIO3
So, the total reaction:
3 I2 + 3 H2O --> 5 HI + HIO3
Now, both HI and HIO3 are colorless in solution, hence the loss of color. However, with exposure to air (meaning O2), per Wikipedia:
"HI will undergo oxidation if left open to air according to the following pathway:[4]
4 HI + O2 → 2H2O + 2 I2
HI + I2 → HI3
HI3 is dark brown in color, which makes aged solutions of HI often appear dark brown."
[Edited on 25-1-2012 by AJKOER]
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