Tuesday, November 29, 2011

Lab Notes: Introduction, Element Collecting and Elemental Iodine

First, an introduction to a new feature of this blog: Lab Notes

As a kid, I was very interested in chemistry. I begged and begged for a chemistry set, finally mom and dad relented and purchased a rather nice one. I spent many, many hours doing the experiments with the set. As I got further along, I found a book that had some more advanced chemistry experiments. Many things fascinated me in the book, but they all looked to be a bit complex, but I saw something that seemed simple, and produced an exciting result; a chemistry class classic, the reaction of potassium permanganate and glycerin. Somehow I convinced my mom to procure KMnO3, and the glycerin. I then did the experiment in a tuna tin. Mom was quite shocked at the result. I was quite satisfied with the 1ft high violet flame. I was also hooked.

I dabbled a bit in reading about chemistry online. It was interesting, but was missing the practicality. I'm finally in a situation where I can do a lot of the stuff I've been wanting to do with chemistry. Now I've bought some glassware (as I get into more stuff that could be potentially toxic, I do not want to use my dishes!) and set about with some experimentation. And with that, I realized I need to keep lab notes, hence, the new blog subject: Lab Notes.

First experiments

A couple of my first experiments were some basic kitchen chemistry, producing sodium acetate out of vinegar and baking soda, concentrating it to the hydrated crystals, and creating a super saturated solution to play with instant crystallization. after a few failures, I had some success, but the product was impure and rather finicky, but did get the instant crystallization I was looking for. I wanted more, and I had been watching a lot of YouTube videos, and found an interesting one to try. It required hydrochloric acid (available at any hardware store as muriatic acid) and hydrogen peroxide. Essentially extracting the bismuth metal from Pepto-Bismol. I haven't done this one yet, but I am planning it. I experimented with a small amount of the HCl and aluminum metal, which dissolved the metal to make a solution of aluminum chloride. It really wasn't surprising and totally expected, also expected was the exothermic nature of the reaction, I was careful to only add small amounts of aluminum at a time to prevent it from heating the plastic cup too much and causing a nasty spill. I eventually moved this outside because of the HCl fumes.

Element collecting

One of my hobbies which started a couple of years ago and inspired by Theodore Gray is the practice of element collecting. I started with coins stamped in various metals (I will one day photograph the coins and share them here), there are elements that aren't currently available as a coin. I added mercury to my collection by harvesting the small glass ampoule from an old thermostat, but aside from the coins (which are most of the transition metals, alkali earth metals, rare-earth metals and some of the non-metals) I was still short on my collection. I wanted more, especially the alkali metals and halides. Neither of which companies are willing to ship due to the reactivity. This is part of the reason for my desire to get chemistry gear, and start doing some home chemistry. The other reason is to investigate was of purifying various substances, such as acetic acid from vinegar, sodium acetate, and so on. I also wanted the lab gear for another hobby of mine: electronics, which to make printed circuits requires some etching chemicals which are rather nasty, toxic and corrosive. I wanted proper handling for these reagents, rather than using something that could potentially be confused with kitchenware.

Preparing Elemental Iodine

So, at Walmart, I was purchasing hydrogen peroxide for the bismuth experiment, when I spotted a tiny brown bottle: Tincture of Iodine! The first thought that ran through my head was elemental iodine. So I bought it and brought it home with me. Last night, while catching up on Youtube, I came across a video, coincidentally, which explained how to isolate the iodine from the tincture. It was simple, and used chemicals and items I already had, so off I went. That's when I noticed something disheartening: It was not tincture of iodine, but tincture of iodides. Hmm. I remember seeing a video on how to extract iodine from potassium iodide (which this contained, along with ethanol, ammonia(!), and ammonium iodide) Ok, so its the same procedure, just a different starting point. No big deal, the ammonia however posed a problem: Iodine reacts with ammonia to produce nitrogen triiodide, which is a contact explosive. I can't have that! So, I started with tiny amounts of everything. a couple ml of the tincture, HCl and hydrogen peroxide. This way, If I do make the nitrogen triiodide accidentally, it will be a small enough quantity that it can be easily dealt with. So, I begin pouring the HCl into the beaker, and (with a bit of dread) noticed it start to fume as I brought the beaker over the one that contained the tincture. Oh, no... not HCl vapors again. I'll have to go out in the cold to finish it. It then occurred to me: I have 2 substances which are giving off a gas, HCl and ammonia. the two combine to form ammonium chloride, the substance of a smoke! This also allayed one of my fears, the HCl would react away the ammonia and prevent the triiodide from being produced. This was good, so I finished the reaction, and proceeded to filter the iodine precipitated from the reaction.

The iodine was then transferred to a small vial and heated to verify that it was indeed iodine, the purple vapor indicated it was what I wanted it to be.

So, now i have a vial of iodine to add to my element collection.