My friend and I are arguing that distilled water does or does not boil. He doesn’t think it boils because there are no inefficiencies and minerals or something like that (I don’t know if that is the right word to use, I am just typing what he said), and I say it does boil, since obviously water boils. So which is it?
It does boil. Your friend may be thinking of superheating, which can be a problem with microwave ovens. See Superheating and Microwave Ovens.
Distilled water boils just fine. The salts and other impurities in undistilled water just raise, or lower, the boiling point a little from the 100°C that pure water boils at. In fact one simple distillation isn’t usually enough to get rid of all the junk in tap water, so many applications call for double distilled water.
Not to be picky here but the process you are describing actually includes distillation, based on the use of boiling point differences to separate constituents and condensation, the subsequent conversion back to liquid form.
Most inorganic constituents pose little trouble in terms of separation, however, organic constituents can be a problem particularly if they form constant boiling azeotropes with water (ethyl alcohol and water is one prime example which is why you cannot get greater than 190 proof - or 95% by volume - ethyl alcohol when you distaill a mixture containing both components.
Also, the latent heat of vaporization of water, approximately 1,000 BTU/#, is so high that other processes such as reverse osmosis offer a better energy utilization for removing impurities.
I seem to recall a ‘hybrid’ phase of water where gas and liquid can co-exist in some superheated water phase. I don’t remember the details, thermodynamics was quite a while back. This would require a pressure change however.
Are you thinking of the triple point of water? If so, then that is on the other end of the spectrum… freezing.
No this was a phase used in power generation.
You’re thinking of “supercritical”. Many power plants operate in this region.
And to add to an earlier post, “superheating” has a much, much broader use than distilled water and microwaves. Most all power plants operate by superheating water.
Why listen to a bunch of self-appointed knowitalls when you can so easily test it yourself?
Thanks Una Persson that’s what I was thinking of.
This should read “most all steam power plants operate…”, duh.
Perhaps a lack of access to pure 18.2 megaohm water is why.
Water at 1 atmosphere (or 14.7 pounds per square inch - psi) of pressure has a boiling point of 212 degrees F. I don’t have my Steam Tables here at home and I’m too lazy to look them up on the internet. For any pressure there is a corresponding temperature on the saturation P-T curve that defines the boiling point.
Superheated steam is the amount of heat that the steam is raised above its boiling point at its saturation pressure. Obviously more energy is required per pound of steam to achieve it but the thermodynamic benefits are seen in the turbines for steam electric generating plants.
So the answer is in a sense that yes, superheat and boiling point are related but as described above it is a relationship based on the P-T diagram for a water-steam system.
Also the ultrapure water used in steam electric plants is to protect the turbine since devices rotating at 1800 or 3600 rpms with massive metal blades that are accustomed to seeing good old steam molecules do not like to be impacted by other molecules and also the biggest culprit is oxygen since it will corrode the turbine blades.
I have access to it! And it boils just fine.
I wonder if the OP is thinking that since impurities in water often form sites for bubbles to form as the water reaches boiling, distilled water would lack nucleation sites and thus couldn’t boil. That’s not the case, but I would think the microwave superheating trick would happen more easily with very pure water.
Don’t forget water-side corrosion in boiler tubes as well.
You are most definitely correct in pointing that out.
However, to get back to the OP, since others are still going there. The unequivocal answer is that water, irrespective of the amount of impurities, will boil along with any other substance already in a liquid state (this excludes those substances that can sublime - go directly from solid to gas without passing though a liquid state). The temperature that water (and all other liquids) will boil at is dependent on the pressure and to a lesser extent to the amount and type (ionized versus unionized) of impurities and the ability of the solvent to ionize measured by the solvents dielectric constant. This is related to the situation where salt (sodium or calcium chloride) can lower the freezing point of water thus its use on roads when the temperature will not go below approximately 17 degrees F.
But does pure oxygenated hexagonal water boil? (WTF is that adpost about?)
Squink may be inaccurate about the ‘double distilled’ water, but most of the scientific community thinks that ddH20 is ‘double distilled’ not ‘distilled, deionized’ so he(?) may still be a smart guy(?).
What kind of person doesn’t have this on tap?
Nah, he’s just old. The advent of cheap, reliable reverse osmosis filters changed the route by which 18+ megohm water is prepared. What used to be double distilled is now often distilled, deionized. The abbreviation dd is ambiguous.
This is why I firmly support the ‘ultrapure’ movement. It means nothing, yet says everything.