Tuesday, December 20, 2011

The sad state of science

This post illustrates in so many ways what is wrong with our world today. To continue stereotyping, and to continue to engrave the idea of blatant consumerism rather than real discovery and science simply disturbs me on so many levels.

I couldn't agree more with Bree. We should cultivate the culture of discovery in all kids, whether they are boys or girls. Arguably, one of the most significant discoveries in the 20th century was made by a woman, and that discovery brought about the nuclear age. (Whether it was a good thing or a bad thing is another matter all-together. That's what the governments did with the discovery...) which among other things helped broaden our understanding of physics, brought about a powerful new source of energy, and gave us life-saving cancer treatments.

Mock Ramblings

Some shameless promotion of a friend's blog:

Mock Ramblings

He's a writer, and posts some rather clever series. If you haven't read any of his writing, you really should! It's good. Real good. One of my favorite (though they haven't made an appearance recently) is Reflections of a Deranged Cultist. Formatted as hijacked blog postings, the deranged cultist, and no sometimes his love interest make postings about the goings on in a secret Cthulhu worshiping cult. What could be more fun? A steel sphere filled with angry porcu-bats, that's what!  

Wednesday, December 07, 2011

Lab Notes: Elemental Iodine - wrap up

In my previous experiment I extracted elemental iodine from Tincture of Iodides. Now to explore how it happens. I knew that the mixture of hydrogen peroxide and hydrochloric acid caused elemental iodine to precipitate from the solution, but didn't understand the mechanism. Now, after a bit of exploring and research, I understand the reaction mechanism. Starting with what is known:

You can see the potassium is left as a positive ion, as the iodine is no longer combined with it. Also note the Iodine was in the -1 oxidation state, but is now in the 0 oxidation state. This means it has been oxidized, not reduced. So, an oxidizer is needed to move the state up one. Hydrogen peroxide is readily available, and at low concentrations is relatively safe to work with. No oxygen was evolved in the reaction between the hydrogen peroxide and potassium iodide, so what is hydrogen peroxide reduced to?

Water and an oxygen radical? Not quite. I'll get to why in a moment.Since no oxygen is evolved from this reaction, I know that oxygen is not generated, so the hydrogen peroxide must be reduced to water. In order for that to occur, there must be hydrogen ions available to balance the equation. So, this pair of half-reactions is most likely:

Adding an acid allows the hydrogen peroxide to decompose to 2 water molecules. After combining the 2 equations, you obtain this equation:

Which is the mechanism behind the reaction. It is a redox reaction, where the Iodine is oxidized, and the hydrogen peroxide is reduced. In my reaction I used hydrochloric acid, so putting everything together, this is the resulting reactants and products:

As you can see, the result is elemental iodine precipitating out of a solution of potassium chloride.

Tuesday, December 06, 2011

Lab Notes: Iron Oxides

For fun, I had this idea: the classic grade-school experiment: making rust. Good ol' iron oxide. So, I grabbed a small row of staples, added some salt, and dropped them in the water.... and waited.

I'm not the most patient person in the world, so I grew tired of how long it was taking to turn steel into rust. Thinking to myself, "Hydrogen peroxide is an oxidizer, therefore, hydrogen peroxide should make the rust faster", and it did. What I ended up with was iron hydroxide, no iron oxide, but with heat it dehydrates, which yielded the black iron oxide, magnetite. Not surprisingly, it's magnetic and quite fun to play with, but it wasn't what I was after, I wanted the deeply red Iron (III) Oxide. When rust forms, it's a mix of oxides and hydroxides. I was hoping to separate the two by somehow driving one into solution, while leaving the other alone. The idea occurred to me by way of a mistake. I had a vial of what was left over after attempting to get a purer form of acetic acid through heat distillation, instead of grabbing the empty vial, I grabbed that one instead, pouring  the magnetic iron oxide into that instead of an empty vial. I noticed that the brown portion was gone, leaving behind only the black. I also noticed that the solution took on a very strong orange coloration. So, I set out to attempt this. Reacted more of the oxide with vinegar (acetic acid), and filtered. To my surprise what came out was a stunningly bright orange solution. What I'm not sure of right now is if it is iron acetate, or iron oxide dissolved in acetic acid. I'm in the process of evaporating the liquid from the solution, and I will see what I get when I rinse the dry product with water.

On another note about the oxidation with hydrogen peroxide, it seems to go much faster with the introduction of sodium chloride (table salt), I don't know the mechanism behind this, but it was very interesting to observe.

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.