97% Sulfuric acid+ KI

[budullewraagh]

well it's expensive and quite impure

[YT2095]

how so?

 

unless the "Cheap stuff" is the most pure!? )

[budullewraagh]

well it's like 5% iodine and 5% potassium iodide. and for that low percent it is very expensive

[YT2095]

at 40p a bottle, I don`t mind the low M, I`de sooner have a small amount 100% pure (medical standard pure) than a load of impure garbage (that may give off brown gas!).

 

it`s all down to personal choice I guess

 

 

 

edit: and the KI isn`t an isue anyway as I convert ALL of it to KI anyway

[budullewraagh]

as you wish. speaking of this reaction, i'm going to be finishing it in a few minutes (maybe). wish me luck...

 

as you can see, i have a really weird solution. i'm going to add 35% h2o2 to it then get the hell out of there in case i get a bunch of bromine. sorta paranoid tho. should i do it?

[5614]

yeah fire away... just leave you camera on constant video mode and then get outta there!!!!

[budullewraagh]

i did. nothing happened. at all. what the bloody hell man

[Gilded]

"i did. nothing happened. at all. what the bloody hell man"

 

Wow, sounds like you shouldn't go near it in a while.

[budullewraagh]

it needs to be acidified a little more. i'll finish it tomorrow

[Gilded]

Hmmh... What sort of camera you used to take those pics, by the way?

[budullewraagh]

panasonic lumix. not exactly great and it was a poor pic. btw, how did i just lose like 20 posts? i was over 1500 earlier...

[Gilded]

"panasonic lumix."

 

Never even heard of such. ) (Although I do know Panasonic )

 

"btw, how did i just lose like 20 posts? i was over 1500 earlier..."

 

That's indeed quite odd, happened to me too. I wonder if when a thread gets deleted, posts are lost from your post count. And if this is true, I bet someone is doing some heavy thread cleaning.

[budullewraagh]

i bet, considering i just lost a bunch again. must...get...over...1500

[Guest Snotty87]

You guys were talking about mixing KI + H2O2..when we did it in school it produced a yellow foam..so I am assuming that it formed water, oxygen, Iodide...and potassium ions?....what happened to the potassium..ive heard many options and i'd like to hear the right one! Thx

[budullewraagh]

eh, actually it was H2SO4 and KI and then H2O2.

H2SO4+KI-->KHSO4+HI

2HI+H2O2-->H2O+I2

 

are you sure you got a yellow foam from KI and H2O2? i personally dont think you did. perhaps there were other reagents used?

[Technologist]

The combination of H2SO4 + KI + H2O2 yields I2 (amoung other things) which is a red/brown ppt depending on your perception. I don't know what the red gas would have been. To be honest I wouldn't have expected a gas to evolve. Was it an exothermic rxn?

[Technologist]

You should set up a shop vac/fume hood in your "home lab" for safety ...

[budullewraagh]

The combination of H2SO4 + KI + H2O2 yields I2 (amoung other things) which is a red/brown ppt depending on your perception. I don't know what the red gas would have been. To be honest I wouldn't have expected a gas to evolve. Was it an exothermic rxn?

we already figured it out. I2 isn't red or brown. it's violet or purple.

my reaction was to first make HI(aq). as i see it, HI(g), a red/brown gas, was evolved with the possibility of a little bromine (another red/brown gas) as well as a little H2S and a bit of SO2. i didn't have a precipitate so there is no iodine. the solution probably is concentrated hydroiodic acid, come to think of it. in such a case, i'd better get rid of it before the feds come in thinking i am starting a meth lab:\

yes, i believe it was exothermic

 

You should set up a shop vac/fume hood in your "home lab" for safety ...

yeah i know but i don't have enough money for that

[ed84c]

Im sure you could improvise.

 

If you bought a cubaord with glass windows (second hand), put a hole in the back, and attatch a pipe ( the tuble dryer type) and an air pump (old vacuum cleaner?), put the pipe through the window and your done!

 

Now you say I2 isnt brown, well i was electrolysing potassium iodate, and got a red liquid out of the anode (i think) what was that then?

[jdurg]

With H2O2 and KI, I can believe that a yellow foam formed. The KI catalyzed the decomposition of H2O2 into oxygen gas and water. A little bit of iodine will be formed, and iodine is VERY slightly soluble in water. If you take some iodine crystals and put them into some warm water, the water will turn a yellowish-brown color from the little bit of I2 that dissolved.

[budullewraagh]

iodine becomes more soluble in the presence of iodide anions. i didn't think the aqueous iodine would be YELLOW though

[Technologist]

Sorry about that, iodine isn’t red/brown, it is a purple. I have a difficult time distinguishing between the colors of bromine, iodine, and other darker shades of these colors. I’m not completely color blind, but needless to say I didn’t pass qualitative analysis with flying colors.

 

Okay, bad joke.

 

I’m fairly positive that hydrogen iodide is a colorless gas with a pungent odor, and in solution is a clear almost yellow liquid. [Edit I also understand its not very stable as a gas? Just offering some additional information ... ]

 

What were your starting reagents and their manufacturer if you don’t mind me asking? Curious to know where the bromine came from.

[budullewraagh]

pun!

 

http://www.al-chymist.com/

i dont like them anymore...while they have good discounts on some things shipping is highway robbery. my reagents were their 95-97% sulfuric acid (technical quality) and their potassium iodide (reagent quality)

[Hexaditon]

With H2O2 and KI, I can believe that a yellow foam formed. The KI catalyzed the decomposition of H2O2 into oxygen gas and water. A little bit of iodine will be formed, and iodine is VERY slightly soluble in water. If you take some iodine crystals and put them into some warm water, the water will turn a yellowish-brown color from the little bit of I2 that dissolved.

 

Yes the addition of H2O2 would (simply) cause rapid decomposition of Hydrogen Peroxide. Iodide ions facilitate the decomposition of H2O2 as seen"

 

Step 1: H2O2 + I- -> H2O + IO-

Step 2: H2O2 + IO- -> H2O + O2 + I-

 

This is pulled out of Chang's 7th ed. I- ion is left as is and serves as only a catalyst. That yellow foam is very accurate. That exact experiment is in this book.

 

The figure's description:

Figure 13.19

The decomposition of hydrogen peroxide is catalyzed by the iodide ion. A few drops of liquid soap have been added to the solution to dramatize the evolution of oxygen gas. (Some of the iodide ions are oxidized to molecular iodine, which then reacts with iodide ions to form brown triiodide ion, I-3)

 

If you need a scan of this please ask and I can make one.

It is infact a deep yellow color and foaming as described. So whomever thought it couldn't be yellow - should try it in a controlled environment.

 

However - perhaps the conc. of the H2O2 is heavier to cause such dramatic results?

 

Food for thought,

Justin

[Hexaditon]

http://64.233.161.104/search?q=cache:2JTVY31Ay5gJ:chemed.tamu.edu/molvis/Summer_02_Learning_Cycles/TJ_tato_Lab-teacher.pdf+%22decomposition+of+hydrogen+peroxide%22+%22iodine%22+%22yellow%22&hl=en

 

http://64.233.161.104/search?q=cache:no8UFT5nj5oJ:chemistry.lsu.edu/webpub/demo-8-kinetics-equilib-cat.pdf+%22decomposition+of+hydrogen+peroxide%22+%22iodine%22+%22yellow%22&hl=en

 

Apparently it's the triiodide ion that creates the yellow color in teh solution