# Heavy Water **URL:** \ **Category:** Factual Questions\ **Created:** [April 26, 2000, 6:03pm UTC](https://boards.straightdope.com/t/heavy-water/11189 "2000-04-26T18:03:00Z")\ **Posts on this page:** 6\ **Page:** 2
**Author:** ![bibliophage](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bibliophage/32/7615_2.png) [@bibliophage](https://boards.straightdope.com/u/bibliophage)\ **Post date:** [April 27, 2000, 5:13am UTC](https://boards.straightdope.com/t/heavy-water/11189/21 "2000-04-27T05:13:00Z")
Natural heavy water apparently is mostly HDO, as I suspected. [Isotopic Composition of Water](http://ucsu.colorado.edu/~jamisons/class/Chap2/observ.htm) gives the HDO proportion of sea water as 320 ppm. Since deuterium makes up roughly 150 per million of hydrogen atoms, there wouldn’t be much left over to make D2O. **If** the isotopes of hydrogen react at random with oxygen, we would expect that by chance only about 25 in one **billion** water molecules would be D2O. By the way, the type of heavy water made with O-18 is 6 or 7 times more common than HDO. The site [BIOTECHNOLOGICAL POTENTIAL OF HEAVY WATER AND DEUTERATED COMPOUNDS](http://www.nbiap.vt.edu/brarg/brasym96/kushner96.htm) says > [@](#): > > The widespread use of heavy water in clinical studies and treatments without reported adverse effects implies that it is not very toxic to humans. This is also suggested by animal experiments, in which toxic effects did not begin to appear until the D content of blood and body fluids and tissues was over 20% (Katz, 1960; 1965; Thomson, 1963). To attain such a concentration and adult human weighing about 70 kg would have to drink rapidly more than 10 L D2O. The site also says C-D (carbon-deuterium) bonds are much stronger than C-H bonds, which surprised me. Also amphetamines “are more readily transported into the brain in the deuterated form.” * * * Work is the curse of the drinking classes. (Oscar Wilde) ---
**Author:** ![Andy](https://avatars.discourse-cdn.com/v4/letter/a/aeb1de/32.png) [@Andy](https://boards.straightdope.com/u/Andy)\ **Post date:** [April 27, 2000, 12:59pm UTC](https://boards.straightdope.com/t/heavy-water/11189/22 "2000-04-27T12:59:00Z")
Aldrich supply 99% D20 at $51-50 for 100g, so it’s not that expensive. And the fact that D2O is hygroscopic is a big problem in NMR spectroscopy. ---
**Author:** ![Andy](https://avatars.discourse-cdn.com/v4/letter/a/aeb1de/32.png) [@Andy](https://boards.straightdope.com/u/Andy)\ **Post date:** [April 27, 2000, 1:18pm UTC](https://boards.straightdope.com/t/heavy-water/11189/23 "2000-04-27T13:18:00Z")
> [@](#): > > Originally posted by Steve-o: > In a first order reaction, the rate of reaction will be about 7 fold slower for the deuterium oxide This ballpark figure is pretty accurate! if anyone’s interested, the term used here is kinetic isotope effect and involves the different rate at which molecules react (as a ratio) when the important site has either X-H or X-D (or even X-T). Commonly, the ‘H’ rates are observed between 1 and 7 times the rate of the ‘D’ molecule. The highest observed was k(H)/k(D) = 24, but this was probably due to tunnelling. k(H)/k(T) = 79 for the same reaction. ---
**Author:** ![C\_K\_Dexter\_Haven](https://avatars.discourse-cdn.com/v4/letter/c/b2d939/32.png) [@C\_K\_Dexter\_Haven](https://boards.straightdope.com/u/C_K_Dexter_Haven)\ **Post date:** [April 27, 2000, 1:21pm UTC](https://boards.straightdope.com/t/heavy-water/11189/24 "2000-04-27T13:21:00Z")
Here all along I thought it was from the famous quote, “He’s not heavy, he’s my water.” ---
**Author:** ![KarmaComa](https://avatars.discourse-cdn.com/v4/letter/k/e36b37/32.png) [@KarmaComa](https://boards.straightdope.com/u/KarmaComa)\ **Post date:** [April 27, 2000, 3:41pm UTC](https://boards.straightdope.com/t/heavy-water/11189/25 "2000-04-27T15:41:00Z")
> [@](#): > > Originally posted by bibliophage: > **The site also says C-D (carbon-deuterium) bonds are much stronger than C-H bonds, which surprised me. Also amphetamines "are more readily transported into the brain in the deuterated form."** So could deuterium get you high, even on an IV drip? ---
**Author:** ![Steve-o](https://avatars.discourse-cdn.com/v4/letter/s/ecc23a/32.png) [@Steve-o](https://boards.straightdope.com/u/Steve-o)\ **Post date:** [April 27, 2000, 4:17pm UTC](https://boards.straightdope.com/t/heavy-water/11189/26 "2000-04-27T16:17:00Z")
> [@](#): > > Originally posted by android209: > **Aldrich supply 99% D20 at $51-50 for 100g, so it’s not that expensive. And the fact that D2O is hygroscopic is a big problem in NMR spectroscopy.** Hey, thanks for the info post adjacent to the one I quoted. Sorry to nit-pick but, by my calculations $50 / 100g = $0.50 per gram. That’s 10 cents higher than the price I quoted of 40 cents per gram (actually 1kg for $424.50 also in Aldrich). By chemical standards, that’s not very expensive, but let’s look at what that would do to the price of a bottle of lotion. I looked at several bottles of lotion here at work, and the average had about 15 ingredients, and all of them had water listed as the primary ingredient. Let’s assume a 16 oz bottle of lotion with the lotion’s density being that of water (1g/mL). Let’s also assume that the D20 makes up 10% of the lotion. 10% of 16 oz (454g) = 45.4g 45g @ $0.40/g = $18 Basically, we’ve just added the whole $18 to the cost of the lotion because, had we used H2O, the cost of the water would have been pennies. [Previous page](https://boards.straightdope.com/t/heavy-water/11189.md?page=1)