Post by: Zer0 on 07/11/2017 15:14:00
act_quickly_and_calmly_when_suffering_a_boiling_water_burn.jpg (4.47 kB . 180x112 - viewed 6050 times)Photo Credits: Magnascan/bigstock.com; Check Man, Cross Man and Jump Man © ioannis kounadeas - Fotolia.com
Post by: Kryptid on 07/11/2017 15:33:09
Post by: Janus on 07/11/2017 16:11:12
Yes. All you have to do is reduce the air pressure enough to lower it's boiling point to that of room temperature or below.Which would be between ~0.0061 and 0.011 atm, assuming a room temperature of ~20C. Below 0.0061 atm, there is no liquid phase of water at all, it goes directly from ice to vapor, in a process called sublimation.
Post by: chris on 07/11/2017 16:57:19
Post by: Bored chemist on 07/11/2017 17:03:35
If the water was at absolute zero - implying no heating - then it wouldn't boil, would it?You cam't get to absolute zero.
Post by: Kryptid on 07/11/2017 20:13:56
If the water was at absolute zero - implying no heating - then it wouldn't boil, would it?
At absolute zero there wouldn't be any energy available to knock water molecules free of the crystal lattice they are in, so no.
Post by: evan_au on 07/11/2017 20:38:03
Quote from: Chris
If the water was at absolute zero - implying no heating - then it wouldn't boil, would it?You can read this from the phase diagram of water.
It looks like there is no liquid phase below about 400 Pa pressure.
This graph bottoms out at 1 Pascal (1 Pa), where there is no vapour phase below -60C.
This is a very low pressure by Earth standards, but still a lot higher than interplanetary space, where the comets hang out...
See: https://en.wikipedia.org/wiki/Water_(data_page)#Phase_diagram
Post by: Bored chemist on 07/11/2017 21:11:56
Post by: evan_au on 08/11/2017 08:58:48
Quote from: boredchemist
Has someone changed the thread title, or do some people think 0K is "room temperature"?I think the conclusion was "Yes, you can boil water at room temperature, by reducing the pressure.".
It then evolved to a related question: "Can water sublimate at 0K?", to which the answer was "No".
...and then onto another related question: "At what temperatures can water sublimate?".
I haven't seen a good answer to this one... Is it around -75C, or does there exist a tiny probability that a water molecule will gain enough energy to jump into the vapor phase, even at 4K?
Would you care to enlighten us, BC?
Post by: chiralSPO on 08/11/2017 17:18:43
Here are some calculations of ice vapor pressures at fairly low temps:
http://www.kayelaby.npl.co.uk/chemistry/3_4/3_4_1.html
And here is a ref about heavy atom (molecule) tunneling (note that the rates are independent of T):
http://comporgchem.com/blog/?p=72
Quote
Below 150 K the Arrhenius curve begins to deviate from linearity, and below 20 K the curve is flat – the rate is no longer temperature dependent! Thus, at cryogenic temperatures, the tunneling rate far exceeds traditional crossing of the variational barrier.
Post by: Bored chemist on 08/11/2017 19:54:26
The verb is "to sublime".
Post by: jeffreyH on 08/11/2017 20:14:05
Post by: Bored chemist on 08/11/2017 21:11:55
0K is the room temperature in quantum hell.Cool!
Post by: Yahya on 09/11/2017 15:10:52
Post by: chiralSPO on 09/11/2017 15:45:28
sorry guys not intending to make fun , but if it is at room temperature then it is not boiling and if it is boiling then it is not at room temperature , you can't combine the two.
Sure you can! Just not at "room pressure"...
Observe:
Post by: Yahya on 10/11/2017 07:58:51
Post by: chiralSPO on 10/11/2017 14:31:28
sorry I did not observe"watch" the video
Experimental observation is one of the central pillars of the scientific method. I have to wonder what are the motives of someone who frequents a science blog, and makes an assertion on a thread, but has no interest in watching the first minute of a video that directly addresses the topic of that thread experimentally.
OP: "Can Water be boiled at room temperature without heating it?"
The video: "look at this water being boiled at room temperature without being heated"
but if they have different pressures then it is not inside the room, it should be a container closed from absolute sides, if so it is another room by itself.
Yes, that's precisely the point. But notice that there is a thermometer in the water, that clearly establishes that the boiling water is at roughly 22 °C, which is within the range that can be considered "room temperature."
Why does it matter that there is a chamber surrounding the water?
Post by: Kryptid on 10/11/2017 17:00:37
sorry I did not observe"watch" the video, but if they have different pressures then it is not inside the room, it should be a container closed from absolute sides, if so it is another room by itself.
You do realize that "room temperature" is not location dependent, right? It's just given that label for convenience's sake.
Post by: Zer0 on 01/12/2017 10:58:40
A - Yes.
*Answer based on subjective interpretation of data/info from the following sources.
https://en.m.wikipedia.org/wiki/Vacuum_evaporation
Vacuum evaporation is the process of causing the pressure in a liquid-filled container to be reduced below the vapor pressure of the liquid, causing the liquid to evaporate at a lower temperature than normal. Although the process can be applied to any type of liquid at any vapor pressure, it is generally used to describe the boiling of water by lowering the container's internal pressure below standard atmospheric pressure and causing the water to boil at room temperature.
The vacuum evaporation treatment process consists of reducing the interior pressure of the evaporation chamber below atmospheric pressure. This reduces the boiling point of the liquid to be evaporated, thereby reducing or eliminating the need for heat in both the boiling and condensation processes. In addition, there are other technical advantages such as the ability to distill other liquids with high boiling points and avoiding the decomposition of substances that are sensitive to temperature, etc.
Thanks & Credits - Wikipedia.
Special Thanks to Factomania for showing the experimental demonstration.