quest
Hazard to Self
Posts: 75
Registered: 15-9-2003
Member Is Offline
Mood: No Mood
|
|
oxidation of KI to I2
I got about 90gr of KI and I want to nake I2 out of it.
I saw a synthesis in frogfot site:
http://www.frogfot.com/synthesis/iodine.html
But my yeilds are poor, about 0.5-1 gr from 10gr KI (and in 100% oxidation i need to get liek 7+- I2 i think....)
Do you know some other easy ways to make I2 from KI?
|
|
|
David Marx
Harmless
Posts: 47
Registered: 13-8-2004
Member Is Offline
Mood: Intrigued
|
|
Did you check out all of Rhodium's assorted methods for the preparation of iodine?
http://rhodium.ws/chemistry/index.html
|
|
|
quest
Hazard to Self
Posts: 75
Registered: 15-9-2003
Member Is Offline
Mood: No Mood
|
|
thx
I searched in this site and found this:
http://rhodium.ws/chemistry/iodine.txt
english is not my nativa language and I didn't understand what thay did there...
so I searched in google "KI+H2O2"
and found this:
http://pubs.rsc.org/ej/CP/2001/b106505j.pdf
here again.....the language barrier....
can some one please wtire this in mroe easily way? maybe only the preparation and not all the background
|
|
|
neutrino
International Hazard
Posts: 1583
Registered: 20-8-2004
Location: USA
Member Is Offline
Mood: oscillating
|
|
Explanations
The 1st one is about using sould waves to make H2O2 and then using that to make I2. The 2nd one is about I2 catalyzing the decomposition of H2O2 to
H2O and O2.
The standard method for making iodine is:
H2O2 + 2HCl + 2KI -> 2H20 + 2KCl + I2.
You can separate most acids for the HCl and most any oxidizers for H2O2.
|
|
|
quest
Hazard to Self
Posts: 75
Registered: 15-9-2003
Member Is Offline
Mood: No Mood
|
|
I tried it
I made some calculation according to the equation you gave,
I first mixed 1.75ml H2O2 with 6.5ml HCl (both 32%) in a test tube.
After the reaction (I think the H2O2 decompose the HCl into H+ ions and Cl2 gas) stoped I took small amount of KI and put it in the test tube, the
liquid turned purple\black I think, and I thought i got myself iodine.
I let the test tube to seat for some hours and hoped the iodine will settle down (iodine doesn't dissolve in water and it got specific gravity
multiply 5 times than water), but he didn't and liquid still looks the same.
So how can I precipitate the iodine?
p.c
sorry for the bad english.....im not an english native speaker :-\
[Edited on 20-8-2004 by quest]
|
|
|
neutrino
International Hazard
Posts: 1583
Registered: 20-8-2004
Location: USA
Member Is Offline
Mood: oscillating
|
|
Actually, you normaly add the KI to one of the other two reactants so it can disociate and form I-. The last reactant is then added and the reaction
produces iodine directly. As for purifying the iodine, I'd try sublimation.
|
|
|
rift valley
Hazard to Others
Posts: 103
Registered: 24-7-2004
Location: NH
Member Is Offline
Mood: semiconducting
|
|
I did the synthesis described by the frogfot link that uses KMnO4. I ended up getting 6 grams of I2 from 10g of KI. It was an interesting experiment.
I probably would have gotten a yield of about 7 grams if I wasn't as sloppy. It does produce noxious fumes so be careful. I2 Is very interesting
as it is the heaviest nonmetal I have ever handeled, and the gas and solid leave a coffee colored stain but it doesnt last long. I give the experiment
a 
|
|
|
JohnWW
International Hazard
Posts: 2849
Registered: 27-7-2004
Location: New Zealand
Member Is Offline
Mood: No Mood
|
|
The poor yields of I2 from oxidation of KI or NaI are probably due to either sublimation, or further oxidation by the H2O2 and/or Cl2 to ICl, IO2-,
IOCl, IOCl3, ICl3, IO3-, or IO4-. The (VII) state is by far the most stable of its positive oxidation states.
John W.
[Edited on 16-9-2004 by JohnWW]
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
