Boiling cold water In a Vacuum Chamber
Why Physics Stack Exchange recommends it
Physics Stack Exchange answerers and commenters link it as a quick visual proof that water boils at room temperature under low pressure and that the boiling cools the water.
Recommended by 0 people across 0 different months, 2015 to 2021.
What it is
A short classroom-style demonstration in which room-temperature water (about 23 C) is placed in a vacuum chamber and boils once the pressure drops to its vapor pressure. A thermometer inside the chamber shows the water cooling as it boils. It is posted by the channel MrGrodskiChemistry.
What people said
Cites Sean · 2015-04 · Physics Stack Exchange · on “Drying clothes with the sun's heat, without any air”
Disclaimer before I get started: A perfect vacuum is impossible. As I answer your question, I will take your use of the word "vacuum" to mean "a chamber with an air pressure arbitrarily close to 0 Pa." When I use the word "vacuum" in my response, I mean the same. Your clothes don't need the air in order to dry, and in fact, will dry more quickly. You've often heard that the freezing point and boiling point of water are 273 K (0 degrees C) and 373 K (100 degrees C) respectively, although that's somewhat sloppy language. The reality is that the freezing point and boiling point of water are 273 K and 373 K at standard atmospheric pressure . The phase of a substance is not only a function of its
Cites David White · 2018-08 · Physics Stack Exchange · on “Definition of boiling point of water”
@user185991, as a class room physics demonstration, I have placed a beaker of 25 C water under a bell jar, pulled a vacuum on it, and caused it to boil at 25 C. As it boiled, its temperature dropped, because the heat to boil the water had to come from the water itself. For an example, see [this video]
Cites David White · 2018-08 · Physics Stack Exchange · on “Lowering of temperature in expansion valve of refrigerator”
@YashMittal, I am posting a link that shows what happens when you pull a vacuum on water, and cause it to boil at room temperature. The thermometer in the water clearly indicates that the water temperature drops as boiling occurs, meaning that the heat to boil the water came from the water itself. The same effect happens to liquid refrigerant going through an expansion valve. Here is the link: [this video]
Cites Vincent Fraticelli · 2019-01 · Physics Stack Exchange · on “If I leave a glass of water out, why do only the surface molecules vaporize?”
I am aware of the possibilities of delaying the ebullition related to the nucleation phenomenon and which depend on the state of purity of the water. But it is known that water in a vacuum chamber boils. For exemple, on Youtube : [this video] Since English is not my native language, I hope to understand your comments properly. (and sorry for my poor english)
Cites David White · 2021-11 · Physics Stack Exchange · on “Why liquid helium boils as its temperature is lowered?”
Regarding the video, it is possible to demonstrate a similar boiling effect with water. If you take a small container of room temperature water (e.g., 25 deg C), place it in a vacuum bell jar, and pull a strong vacuum on it, you will find that at a low enough pressure, the water starts boiling with no apparent heat source causing that boiling. Water has a vapor pressure that is dependent only on its temperature, and when the ambient pressure inside the bell jar reaches the vapor pressure of the water, the water will boil. The heat for that boiling comes from the water itself, and as a consequence, the temperature of the water drops as boiling proceeds. This means that you can take the temper