This is a true story about a true chemistry geek (i.e. I).
In my AP Chemistry sojourn, I've learned quite a few chemical principles. From why the ionization energies of molecules have their patterns, to calculating an equilibrium constant using the Gibbs' free energy expression. And more recently, electrolysis.
A recurring theme in AP Chemistry is putting an ionic solid in aqueous solution (i.e. putting salt into water), running an electric current through it, and predicting what compounds should form.
Some chemical background (WARNING: NOT FUNNY)
The advantage of electrolysis is that the redox reaction that occurs doesn't need to be spontaneous, because you're providing electrical/chemical energy from an outside source (a battery). You are forcing the reaction to happen, instead of the reaction happening on its own.
There is a limiting factor, however: one can only oxidize or reduce the compounds that require the least amount of energy to oxidize or reduce to form their compounds. You have a bunch of chemical candidates for oxidation (losing electrons), and a bunch for reduction (gaining electrons). The compound in the solution that actually undergoes oxidation or reduction will be the one that requires the least energy to happen. Mathematically, the half-cell potential has to be the least negative.
(Yes, I know this is boring. I'll get to the funny
You start by putting salt into water, under standard conditions (25 degrees Celsius and 1 M NaCl, or approximately 58-59 grams of salt per every Liter of water). Just put in a bit of salt and mix. This make the water electrolytical, with ions to conduct a current. You can electrolyze it by taking a battery (a 9 V will do; I used 3), attaching alligator clips to the terminals, clipping the other ends of the clips to inert electrodes (such as graphite rods or platinum), and then sticking those into the salt water solution. the products of electrolysis will be O2 gas and hydrogenH2 gas:
2H2O + 2e- --> H2 (g) + 2OH-
4OH- --> 2O2 (g) + 4e- + 2H2O
If you dump in a bunch of salt, however, something more interesting and dangerous occurs. By making it really concentrated, you can make chlorine gas instead of oxygen. This phenomenon, called "overvoltage," occurs because there's so much chloride ion (Cl-) in the solution that the chloride, and not the oxygen, gives up electrons. Thus forms chlorine gas. For chemistry nerds out there, this is a result of the Nernst equation.
The people you know
Our AP Chemistry class is full of characters. One such person is Will Petry, a chemistry and biology dork who plays with chemicals at home. One morning during lab, he tells us the tale of how he made chlorine gas, and subsequently bleach, in his own basement the night prior. His little brother was there watching. Mr. Marx, later, called his mother and told her this, making sure she knew that it was dangerous, but that he had also petrified most of the cockroaches in his basement. (With more precise apparati, you can petrify a cockroach with this experiment)We pointed and laughed at him for being a loser.
Not wanting to be out-losered, I decided that I would follow suit that night.
First I got three Energizer 9 V batteries, two alligator clips, and a glass of concentrated salt water. I also got a bunch of paper clips to use.
Trial 1: No duh.
I took the three nine volts and connected them together at their terminals. The alligator clips were huge, and when I tried to attach them to leftover terminals they kept falling off. Once I had performed some magical form of yoga on these clips, they stayed attached to the batteries. I attached the othe ends of the alligator clips to paper clips. The 27 V series battery I made was top heavy and kept falling over.
Drinking glass in hand, I dumped in a bunch of sea salt and doused it in filtered water from the refrigerator. I took the experiment to the outside deck and set it up above our hot tub (which had a covering over it). I then commenced the experiment by putting the paper clips into the glass. This was perhaps the most ghetto electrolysis experiment ever conducted (no pun intended).
What happened startled me. From one paper clip, hydrogen gas was bubbling off. I collected this in a glass and put a gas lighter inside the glass to see the pretty flames. yee.
What happened at the other paper clip, where chlorine should have formed, startled me. A murky green tendril glided off that paper clip. After a prolonged time, those tendrils settled into green shrouds and clouds in the solution, varying in thickness and color intensity. I thought, perhaps the chlorine gas stayed inside the glass for some reason, but it seemed wrong. Nonetheless, I took pictures of this and put them on Facebook.
I asked Mr. Marx, my AP Chem teacher, what had happened. It turns out I neglected the presence of the metal paper clips in my predictions. What actually happened was that metal from the paperclips were being oxidized into ions. Probably some iron and copper ions formed, which made the solution blue-green ish. Well then.
This was confirmed by the fact that one paper clip looked slightly disintegrated after the experiment.
Nonetheless, I was having fun touching the paper clips together, watching the bubbling stop and start in the liquid. Outside the liquid, I touched the paper clips together, which formed sparks. Oooh pretty. Yay for being a chem dork.
TODAY'S EXPERIMENT: ...FAILURE.
Trial 2: Wow, that was dumb of me
A few weeks later. I knew what I had to do: choose a different electrode. I skim my standard reduction table (standard fare on all AP Chem tests) for a metal that won't oxidize before chlorine.
I decided on aluminum.
To acquire this, I did the most logical thing: drink a black cherry soda and tear up the can.
...Or, even more logical, I could have just grabbed some aluminum foil. Oops.
So now I have many forms of aluminum to use.
I went outside, and oxidized. This time I took safety precautions: after attaching the aluminum to the alligator clips, I bent them so that the clips could rest outside the solution. Some voodoo eventually made them rest over the glass inside the solution without my hands. I then took another glass and scotch-taped it over the glass with the solution. This way, all the gas would be trapped in the glass, and I'd be safe.
...Sure, Hydrogen formed. But again, the scrap of aluminum emitted a tendril of ... gray stuff? WTF. After some time, the aluminum "curled up" and resided just at the surface's solution.
Turns out I misread the standard reduction table: aluminum fucking oxidized goddammit. no chlorine gas.
...Now I'm sure you may be wondering why I'd be wanting to make chlorine gas at this point. Considering that it is extremely poisonous and could kill me. Well, I'm a chemistry dork. I can brag about it to people who will then laugh at me. Plus, it makes bleach (which I would have wanted to test out on some clothes.)
So I knew what I had to get now: Platinum or gold. Now, where could I get such lustrous and expensive metals?
"Hey mom, do you have any platinum jewelry?"
She offered me some white gold, an alloy of platinum and gold that oxidizes rather easily in the air. After looking stuff up on Wikipedia, though, I found it had other elements that could be oxidized. I would essentially destroy her jewelry, had i used it.
Why she would nod assent to such an experiment with her jewelry, I have no clue.
Next, I asked if she had any gold, "preferably 24 karat."
Alas, she had only 12 karat gold. Again, some Wikipedia searching yielded that 12 karat gold was a bit over 50% gold. Still significantly an alloy. This made me hesitant, but I went with it.
"Mom, if you let me do this, there is the potential that I could kill myself AND ruin your jewelry."
"Well, don't ruin the jewelry."
...Right. Whatever the the hazards I was ready.
Once more, undeterred by these devious metals who enjoy oxidizing so goddamn much, I set forth the current through these two golden rings.
Three things happened all at once. At one ring, there was a slight green tinge emanating. There was also the faint smell of chlorine. ... And the ring began losing its luster. stercus stercus stercus...
Certainly I made chlorine gas. ... But gold also loves to react with chlorine gas. It forms the red-brownish ionic solid Gold(III) chloride. This solid is soluble in water. SO essentially, the chlorine came off the earring and reacted with the gold, forming the ionic solid which then dissolved in water.
We were able to polish some lustrousness back into the earring. Luckily my mom doesn't wear those earrings much anyway.
...My mother then went online and forced me to buy some carbon/graphite rods.
Trial 3: Why I'll Never Have A Girlfriend
A week later the graphite rods arrive. I set up the experiment again.
It worked. I smelled the chlorine gas. And some small amount of bleach. The chlorine gas smelled like the laurels of victory, only more poisonous and deadly. Indeed, it was a dangerous win.
I then turn into an electrolysis monster. What else can I do?
Remembering that bleach reacts with ammonia (which is found in urine), I took a piss and checked to see if anything dangerous happened. Nothing. Must not have made enough bleach, oh well.
Then I tried to electrolyze my own urine. I don't think this did much at all though. Considering that most everything in urine is at such a low concentration, I'm sure all I made was some foul smelling hydrogen and oxygen.
1. Chlorine gas smells like... well, pool water. No surprise.
2. I didn't make much bleach.
3. Never use gold jewelry as an electrode.
4. Electrolyzing urine does nothing interesting.
5. I'll probably never have a girlfriend