10 Ho hum… what a relaxing break. I don’t remember the last time I stayed away from lab that long… it’s refreshing.
Now I have to motivate myself to start doing things. I found a reaction that I left going over the break and have decided to work it up – sort of a warm up for real chemistry. I figure a little column chromatography and some basic extractions will put me back in the mood for chemistry.
As you know I’m an enormous nerd, so when Mrs. Finchsigmate delivered my totally awesome Hanukkah/Saturnalia gift (we are a mixed household) of a 37 gallon fish tank (with an Eclipse hood!) I just had to run to the fish store and purchase all sorts of various chemicals with which to dump into the toxic waste water that oozes from my tap to make it reasonably safe for little fishies. The first thing I purchased was something called Tap Water Conditioner from Aquarium Pharmaceuticals. The shit is supposed to reduce the amount of “toxins” in your tap water, which I suspected to mean heavy metals and chlorine. Removing heavy metals is easy, what with the advent of EDTA According to the product’s MSDS that is in there. What I didn’t know is how you remove chlorine from tap water… NOW I DO!
Sodium thiosulfate is the other chemical in this precious fluid of fish love, a compound which I’ve used in the lab for a number of unrelated purposes. Chloramine and Hypochlorous acid are essentially the result of dissolved chlorine in water (chloramine obviously requires the presence of ammonia, not altogether hard to pickup in groundwater. Indeed, chloramine is ADDED to water now because it is more “environmentally friendly” than chlorinating the water. Chlorinating the water can cause the formation of chlorinated hydrocarbons – stuff like chloroform and carbon tet. Bad stuff.) Hypochlorous acid is eliminated when water sits around for a while (interestingly enough, distillation does not eliminate chlorine from water, it moves right with the water vapor. The only way to remove it is to chemically treat it or just let it sit in the open). My best guess is the elimination of Hypochlorous acid occurs after deprotonation with sodium thiosulfate to make the mostly decent oxidant Sodium hypochlorite. This oxidant will thus go on to oxidize thiosulfate into Tetrathionate and turning the hypochlorite salt into salt (NaCl) water.
Chloramine isn’t so easy to get rid of. The corresponding reaction to remove chloramine isn’t so clear to me. I can’t think of many things that would favor oxidation of nitrogenous compounds in a plastic bucket of water with sulfur. My best guess is that it doesn’t actually do anything to the chloramine itself but, rather, relies on the equilibrium between chloramine and hypochlorous acid and ammonia (which I can’t imagine to be a very fast process… but I know nothing, really. ) :
NH3 + HOCl ↔ NH2Cl + H2O
I found this reaction on the internet, but I’m pretty sure it’s complete bullshit:
S2O32- + 4NH2Cl + 5H2O → 2SO42- + 2H+ + 4HCl + 4NH3
I doubt that thiosulfate is strong enough to oxidize chloramine and I’ll bet it goes through the thiosulfate decomposition product, sulfite. That website gives alternate possibilities. No matter what you do, I can only see this reaction liberating ammonia into the water, something little fishies aren’t too fond of either.
I had to purchase new fish to help cycle the tank, so I went to Petco and obtained five feeder goldfish named after my second, third, fourth, fifth and sixth favorite chemists (in no order, actually):
| Name | Status |
|---|---|
 Danishefsky |
Dead |
| Trauner |
Dead |
 Whitesides |
Sickly |
| Danheiser |
Dead |
| Stoddart |
Healthy! |
Well… naming my fish after awesome chemists didn’t seem to impart awesome luck on them. Sir Fraser is the only one that is clearly doing well. *sigh*
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George’s assistant recently purchased a Betta fish for her office. I feed the little guy on weekends, and we’ve nursed him back to “vibrant” status from “sickly.” It can be done! (Don’t let little G die on me.)
The sodium thiosulfate products (photographic hypo) only remove the chlorine, tha mmomonia is left behind. It may not be a problem for the system in the small amounts used in these municiple water systems, so long at the pH is on the acidic side. The presence of protons at pH of below 7.2 and ammonia ends up making ammonium (NH4+) which will generally not cross biological membranes and not damage the gills of your fishes, however, as of late, many muni’s add buffering to the water to keep the pH in the 8 to 9 range, keeping the pH at a level where the ammonia will stay as NH3, the unionized form, where even low levels (2 ppm) may cause gill clubbing and damage. Depending on concentration an pH of the water, damage can accumulate over time to kill the fih.
Best to either use distilled water or RO/DI at less than 4 TDS for top off, use Granular Activated Carbon to run the water through to remove the ammonia, use ammocarb (better) to do the same and neutralize the ammonia, or test the pH of the water after treatment with a pH probe (papers are generally not reliable enough) and/or your total ammonia concentration.
HTH,
Tom
Yay for Fraser Stoddart!
yay! Dirk made the 2 through 6 list
Actually that should be Sir Fraser Stoddart! See
http://www.cnsi.ucla.edu/news/item?item_id=230184
Is that a resonance arrow being used to depict an equilibrium? Shame!
Yes. If you can find me the ASCII equivalent of an equilibrium arrow, I’ll change it.
Welcome back to el bloggitoland. You were missed.
I’m glad Sir Fraser is still alive, if only cause among your top 2-6 he sounds the most like Sean Connery.
You must embrace the philosophy of the fish tank. What is path compared to goal? Consider the Congressional aquarium: A breeding pair of Betta splendens and the lower ranks work it out amongst themselves. The result is Ted Kennedy surrounded by lots of Nancy Pelosis. Bet you don’t see that in the wild.
Feeder goldfish are great for contaminating artificial lakes. They’ll reach 25 cm length and live 20 years. The only better surprise is wild-type Xenopus laevis. Give them a couple of years and they’ll go after swimmers.
Have you looked at KDF filtering? It supposedly removes chloramine but I’m not sure how (I’m just an amateur chemist). KDF is used in shower and bath filters.