Can you carbonate heavy water?

May 4, 2009 7:06 AM

Could you carbonate heavy or super-heavy (tritiated) water?

Suppose you had a bunch of mostly-pure heavy water (deuterium) or super-heavy water (tritium). Would you be able to carbonate these? It seems like heavy water, at least, has similar properties to "normal" water, but I'm not sure if the differences would affect carbonation.

posted by Godbert to science & nature (8 comments total)

As an undergrad chemistry major I fooled around a little with deuterated water as a solvent in NMR spectroscopy; unlike regular hydrogen, deuterium does not give an NMR signal making it easier to study the solute. Since carbonation is nothing more than dissolving CO2 in water, I would think the results would be very close, although there are some slight differences in the chemical properties of heavy water.
posted by TedW at 7:19 AM on May 4

Nah, not at that level.

It turns out that neutron number can affect chemical properties, but it's at an incredibly low level. Many, many decimal places. Carbonate away!
posted by adipocere at 7:19 AM on May 4

As a further note, it appears your exact question was answered in 1938, but I have been unable to find more than the first page of the article; I will keep looking though.
posted by TedW at 7:22 AM on May 4 [4 favorites has favorites]

I e-mailed a PDF of that article to both TedW and Godbert.
posted by grouse at 7:35 AM on May 4 [3 favorites has favorites]

To complete the question, the conclusion of the paper mentioned by TedW is that the solubility of carbon dioxide in water and heavy water was measured to differ by less than 1%.
posted by toftflin at 10:55 AM on May 4 [1 favorite has favorites]

You'd have a serious problem with the tritiated carbonated water.

It would go flat very, very rapidly, and I would expect it to foam out of a bottle whenever you opened it the way ordinary carbonated water at a comparable level of carbonation does only when you shake it.

This is because the high energy electrons emitted by the tritium when it decays would produce ion trails in the water which would act as centers of nucleation for the dissolved carbon dioxide. A slight variation of this process is actually one of the basic ways of detecting radiation in the form of a bubble chamber.
posted by jamjam at 12:20 PM on May 4

That'd make one hell of a cocktail.
posted by leotrotsky at 12:38 PM on May 4

jamjam, nice point. The electron in tritium decay is probably too slow (6 keV on average) to make much of an ion trail, but the radiation effects are probably important.

Completely tritiated water would be interesting stuff. In each cubic centimeter you'd have about 0.1 joule per second heat deposited from the beta decays of tritium to helium. The betas would put all their energy into the water and so, far from any surface, the temperature would rise one degree Celsius every forty seconds. A volume of completely tritiated water in a well-insulated container would go from freezing to boiling in about an hour.

Also, a volume of completely tritiated water would, every hour, put off an equal volume of helium-3 gas. Also each decay would turn a T₂O into a He and an OT in various charge states. The extra OT (hydroxyls? tritoxyls?) would make the tritiated water act like a base (I think). Eventually there would be enough of them that they could combine into water and oxygen, and the liquid would give off O₂ at half the rate of ³He. It might also give off some T₂ gas. Figuring how much takes more chemistry than I know.

The reason carbonated drinks foam when you open them is that the equilibrium concentration of dissolved CO₂ depends on the partial pressure of CO₂ in the atmosphere around the liquid. The earth's atmosphere has only about 0.3% carbon dioxide, so a carbonated liquid that's left open to a room will go flat. But if you enclose the liquid it can build up its own carbon dioxide atmosphere, until CO₂ molecules entering and leaving solution are in equilibrium. When you open a soda bottle you suddenly change the CO₂ partial pressure, and so the gas comes out of solution as fast as it can.

If I read the Curry and Hazelton paper posted by TedW right, changing the isotopic composition of water doesn't measurably change the volume-per-volume amount of carbon dioxide that can be dissolved. That's probably also true for tritiated water. It might be the case, as jamjam suggested, that the high density of free charge in tritiated water would make the transition where CO₂ comes out of solution faster than in light water. But if a liter of tritiated water puts out, every hour, a liter and a half of helium, oxygen, and tritium gases, you would have to store it in a vented container. The carbon dioxide coming out of solution would also get vented. It would take some clever trickery to store carbonated superheavy water for any length of time.

What a fun problem! Everyone I know who uses or wants to use tritium wants T₂ gas. I'll have to watch for a chance to play with this.
posted by fantabulous timewaster at 9:06 AM on May 7 [1 favorite has favorites]