symboom - 23-12-2016 at 21:18
So ive been trying to synthesize sodium bromate and potassium iodate from potassium iodide and sodium bromide
Using hypochorite to oxidize bromide and iodide to hypoiodite and hypobromite then disproportionate to iodate and bromate
This avoids the use of electricity and halide
gdflp - 23-12-2016 at 22:43
I have prepared potassium iodate from the iodide using permanganate as the oxidant instead of hypochlorite. Quick, easy, and high yielding. IIRC, a
ref claimed that bromide salts could be oxidized by permanganate as well, but I never tried it personally.
The hypochlorite oxidation sounds superior due to the greater availability of the oxidant, as well as a cleaner reaction(MnO<sub>2 </sub>
can get quite messy).
The only thing that concerns me about using hypochlorite is the potential for chlorate contamination in the final product. Have you ascertained the
purity in any way?
symboom - 24-12-2016 at 04:40
I have looked through lots of solubility charts and calcium iodate is not very soluble
Sodium bromate is also not as soluble as sodium chlorate
May the least soluble one win
[Edited on 24-12-2016 by symboom]
[Edited on 24-12-2016 by symboom]
[Edited on 24-12-2016 by symboom]
AJKOER - 24-12-2016 at 11:59
To lessen the likelihood of chlorate formation or other not intended products, I would avoid strong light as iodide salts can be photo active capable
of producing a hydrated electron, for example, see "Critical Review of Rate Constants for Reactions of Hydrated Electrons, Hydrogen Atoms and Hydroxyl
Radicals", at https://www.google.com/url?sa=t&source=web&rct=j&... .
Also, application of heat generally favors chlorate formation, so cooling the reaction mixture should mitigate their creation.
[Edit] There is some understanding of the role of transition metals salts in promoting cancerous bromate formation from bromide in chlorinated water.
The introduction of catalytic copper/nickel by passing water through copper pipes (offering surface exposure to CuO and NiO) has been attributed to
bromate formation. See, for example, "Chlorination of bromide-containing waters: Enhanced bromate formation in the presence of synthetic metal oxides
and deposits formed in drinking water distribution systems" by Chao Liu, available at https://www.google.com/url?q=http://scholar.google.com/schol...
Here is a reference to prior research (from an article favoring the use of ClO2 in water distribution systems) noting, to quote:
"The catalytic disproportionation of ClO2 is in line with our previous observation, which showed that CuO could catalyze the disproportionation of
HOCl and HOBr"
Link: https://www.researchgate.net/figure/241696320_fig1_Figure-1-...
which suggests to me that the employment of CuO as a catalyst (or present as an impurity) could lead to an increase in both chlorate and bromate
formation.
Here is a typical health concern article with respect to bromate http://www.sciencedirect.com/science/article/pii/S2214750014... .
[Edited on 25-12-2016 by AJKOER]
[Edited on 25-12-2016 by AJKOER]
What is going on here :/
symboom - 25-12-2016 at 02:12
Now im worried I dont know what I formed. Using calcium hypochlorite mixing with sodium bromide and potassium iodide
The sodium bromide has a lemon yellow solid and the iodine has a red solid percipitate both also has the same colored liquid as the solid
Then again maybe the calcium hypichlorite did not dissolve
Interhalogen doesnt explain it
Calcium hypoiodite and calcium hypobromite maybe
Forming calcium chloride as a result
[Edited on 25-12-2016 by symboom]
[Edited on 25-12-2016 by symboom]
[Edited on 25-12-2016 by symboom]
The reaction showing chlorate oxidizing iodide
symboom - 5-1-2017 at 04:31
Iodine chlock reaction with chlorate
An experimental iodine clock sequence has also been established for a system consisting of iodine potassium-iodide, sodium chlorate and perchloric
acid that takes place through the following reactions.[3]
Triiodide is present in equilibrium with iodide anion and molecular iodine:
I3− → I− + I2
Chlorate ion oxidizes iodide ion to hypoiodous acid and chlorous acid in slow and rate-determining step:
ClO3− + I− + 2 H+ → HOI + HClO2m
Chlorate consumption is accelerated by reaction of hypoiodous acid to iodous acid and more chlorous acid:
ClO3− + HOI + H+ → HIO2 + HClO2
More autocatalysis when newly generated iodous acid also converts chlorate in the fastest reaction step:
ClO3− + HIO2 → IO3− + HClO2
In this clock the induction period is the time it takes for autocatalytic process to start after which the concentration of free iodine falls rapidly
as observed by UV/VIS spectroscopy
Reference wikipedia iodine clock reaction
[Edited on 5-1-2017 by symboom]