dubois928 Posted December 2, 2007 Share Posted December 2, 2007 When I burned a few drops of Iodine Tincture on a thin piece of aluminum, a very minute amount of light gray-brown powder was left. What is it? Thanks, Kenneth Anderson Link to comment Share on other sites More sharing options...
Melvin Posted December 2, 2007 Share Posted December 2, 2007 It could be aluminum triiodide. If its pure, it would be colorless, but small impurities will make it brown. Link to comment Share on other sites More sharing options...
YT2095 Posted December 2, 2007 Share Posted December 2, 2007 also Iodine tincture is made with KI also, the ions from that help with the solvation of the I2. Link to comment Share on other sites More sharing options...
Melvin Posted December 2, 2007 Share Posted December 2, 2007 I read somewhere that elemental iodine can be produced from copper(II) sulfate and potassium iodide. Would aluminum iodide work in place of KI? What about FeI2? Link to comment Share on other sites More sharing options...
vampares Posted December 4, 2007 Share Posted December 4, 2007 When I burned a few drops of Iodine Tincture on a thin piece of aluminum, a very minute amount of light gray-brown powder was left. What is it? My guess is magnesium from the aluminum alloy. :S Link to comment Share on other sites More sharing options...
YT2095 Posted December 4, 2007 Share Posted December 4, 2007 no, alu foil is actually surprisingly Pure, to at least 2 decimal places back! yeah I know, I was quite astonished to find this out too I`m not sure about the CuSO4 + KI rxn??? the easiest way normally is displace it with another Halogen further up the group. if I get time in the morning (and I remember) I`ll try it and let you know Link to comment Share on other sites More sharing options...
John Cuthber Posted December 4, 2007 Share Posted December 4, 2007 "no, alu foil is actually surprisingly Pure, to at least 2 decimal places back! yeah I know, I was quite astonished to find this out too :)" Sure about that? Decimal places of what? http://www.enotes.com/how-products-encyclopedia/aluminum-foil http://www.key-to-metals.com/Article119.htm Also, in my experience it often leaves stuff behind when you dissolve it in alkali. It's possible that the blackening refered too in the first post is bits of other alloy elements trapped in a (mainly KI) matrix. Anyway the 2Cu++ + 4I- --> 2 CuI +I2 reaction is a classic for measuring Cu++ in solution. The problem is that you lose half the I as CuI. Peroxide and acid seems to be the method of choice for the amateur scientist but there are lots of possibilities. Link to comment Share on other sites More sharing options...
dubois928 Posted December 5, 2007 Author Share Posted December 5, 2007 Well it actually isn't aluminum foil, its a strip I cut off of a washed soda can. I used the un-printed side, though. Link to comment Share on other sites More sharing options...
John Cuthber Posted December 5, 2007 Share Posted December 5, 2007 The insides of drinks tins are varnished. Did you clean that off? Link to comment Share on other sites More sharing options...
dubois928 Posted December 6, 2007 Author Share Posted December 6, 2007 I don't know. It doesn't look varnished to me. But I only cleaned it out with water. Maybe I'll try it on something else and see if it does the same thing. Ken Link to comment Share on other sites More sharing options...
Melvin Posted December 6, 2007 Share Posted December 6, 2007 I would take a piece of Al can and a piece of Al foil. Add equal amounts of iodine tincture to each, then light. Compare the two when finished:-) Link to comment Share on other sites More sharing options...
John Cuthber Posted December 6, 2007 Share Posted December 6, 2007 Many soft drinks are acid enough to corrode a clean aluminium surface. Link to comment Share on other sites More sharing options...
Mr Skeptic Posted December 6, 2007 Share Posted December 6, 2007 Many soft drinks are acid enough to corrode a clean aluminium surface. Is that scary, or what? Link to comment Share on other sites More sharing options...
Melvin Posted December 7, 2007 Share Posted December 7, 2007 Is that scary, or what? That is kinda scary! But, you have to remember that your very own stomach contains HCl, which is much stronger than the H2CO3 in soft drinks. I assume that aluminum corroded by soft drinks is aluminum carbonate? Link to comment Share on other sites More sharing options...
YT2095 Posted December 7, 2007 Share Posted December 7, 2007 there`s also Citric and Phosphoric acid in quite a few of these drinks, the later is a very strong acid, not as strong as sulphuric but stronger than Nitric! and Thankfully Non-Toxic Link to comment Share on other sites More sharing options...
encipher Posted December 11, 2007 Share Posted December 11, 2007 there`s also Citric and Phosphoric acid in quite a few of these drinks, the later is a very strong acid, not as strong as sulphuric but stronger than Nitric!and Thankfully Non-Toxic How is Phosphoric acid stronger than nitric acid? Phosphoric acid is clearly classified as a weak acid, and nitric as strong. Link to comment Share on other sites More sharing options...
TiffanyAyala Posted January 19, 2018 Share Posted January 19, 2018 (edited) You have to know it from one service. https://www.nterlearning.org/forum/-/message_boards/message/3548792 here I saw a link to it. Try to seek there. I hope it'll help you! Edited January 19, 2018 by TiffanyAyala Link to comment Share on other sites More sharing options...
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