Date: Fri, 25 Sep 2009 17:15:44 -0400
Reply-To: "Dr. Jay A. Young" <chemsafety**At_Symbol_Here**VERIZON.NET>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: "Dr. Jay A. Young" <chemsafety**At_Symbol_Here**VERIZON.NET>
Subject: Re: Iodine corrosivity
Comments: To: List Moderator

And after the iodine gets through the zinc coating it reacts to make BEAUTIFUL FeI3 crystals.  Try it sometime, it is a lovely reaction, especially if you pass I2 vapor over hot iron filings in a closed system, of course.
The FeI3 crystals form and then fall like colored snow toward the bottom of the reaction space.
Jay Young
----- Original Message -----
From: List Moderator
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Sent: Friday, September 25, 2009 11:08 AM
Subject: Re: [DCHAS-L] Iodine corrosivity

From: Wayne Wolsey <wolsey**At_Symbol_Here**>
Subject: Re: [DCHAS-L] Iodine corrosivity
Date: September 24, 2009 4:09:29 PM EDT

If the metal trap is galvanized iron, meaning zinc-coated, certainly zinc will react spontaneously with I2 in a redox reaction giving Zn2+ and iodide, I- .  The same thing can happen with aluminum, with similar chemistry.

Wayne Wolsey
Professor Emeritus
Macalester College
St. Paul, MN

From: Ernest Lippert <ernielippert**At_Symbol_Here**>
Subject: Re: [DCHAS-L] Iodine corrosivity
Date: September 24, 2009 5:39:12 PM EDT

Based on the observed results, elemental iodine will corrode a metal trap. A knowledge of basic descriptive chemistry, as it was once taught, bears this out. There are a couple of things wrong here, not the least of which was an incorrect disposal method. A plumber should have been called to remove and clean the trap. His visit would be followed by proper disposal of the residue. If this couldn't have been done and as a last effort, the teacher perhaps should have known that iodine is much more soluble in a solution of potassium iodide than in water. On the other hand, is it preferable to have a leak with its obvious local contamination followed by proper disposal of the residues than it is to discharge a (significant) amount of iodine and KI into the sewer system?

Ernest Lippert

From: Robert Weeks <rweeks**At_Symbol_Here**>
Subject: Re: [DCHAS-L] Iodine corrosivity
Date: September 25, 2009 10:57:28 AM EDT

Certainly a possibility. Might be interesting to perform  surogate experiments w/iodine crystals and pieces of pipe metal. Do the experiment w/iodine crystals, w/whatever else might have gone down this drain, and then w/iodine crystals plus whatever else might have gone down the drain.

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