ScienceHideout - 8-4-2011 at 19:03
Could I be the first to think of this?
When Kekule made benzene, he freezed it seperating it from water. HNO3 has a freezing point of -42 centigrade. Why couldn't we stick it in an unused
freezer overnight, and decant the acid from the ice?
Sedit - 8-4-2011 at 21:58
More then likely because the HNO3 will act simular to a nitrate salt and lower the freezing point of water. As so there would be no ice to seperate on
cooling.
ScienceHideout - 9-4-2011 at 07:04
We could lower the temperature of our freezer to, see if there is any way to make it near -10 centigrade, or colder.
UnintentionalChaos - 9-4-2011 at 18:14
Anything dissolved in water will cause a freezing point depression. On a more complex note, nitric acid/water has a very complex phase diagram. See http://www.charis.wlc.edu/publications/symposium_spring02/ha...
If I remember how to read these right, all you can do with -10C is to bring nitric acid below 15% up to about 15% concentration by freezing out some
water. If you can take such a dilute solution down to -40C or so, you can boost it up to 32% which is a eutectic, and you can't do better than that by
freezing with dilute solutions. Also keep in mind that the entire filtration needs to be done at the freezing temp lest the solid melt and dilute the
filtrate.
At the high end of the concentration spectrum, you can freeze the nitric acid out of solution (maybe, it looks rather complicated), it seems but that
requires very low temps.
[Edited on 4-10-11 by UnintentionalChaos]
[Edited on 4-10-11 by UnintentionalChaos]