Boiling water

[Tomcat]

@UncleRojelio

Unless something has gone terribly wrong, 1 atmosphere.

I was just wondering if it was like 1.1 or 1.2 atmospheres or ??? Airplanes are pressurized to 8000 ft (as I recall), not sea level.

-Tcat

[Praetor]

@Tapioca Dextrin

Was it salty water?

He’d have to have an awfully concentrated solution to have the boiling point increase by ~5 degrees C (on the order of 5 molal for a salt that dissociates into 2 ions). For reference, sea water is ~0.6 molal.

[flight]

@Praetor

He’d have to have an awfully concentrated solution to have the boiling point increase by ~5 degrees C (on the order of 5 molal for a salt that dissociates into 2 ions). For reference, sea water is ~0.6 molal.

More liekly the thermometer was just resting on the bottom of the pot.

[Hari_Seldon]

I believe that the critical point of water (the temperature above which it cannot remain liquid at any pressure) is somewhere over 300 deg C, which ought to be around 600 deg F. At that temperature, it just changes into the gaseous state without boiling.

The critical point of carbon dioxide is 45 deg C and that was the basis for one of the methods of preparing biological specimens for the electon microscope with destoying delicate membranes from surface tension.

[CookingWithGas]

@David Simmons

Water can also be supercooled below 32 F if it is very still.

Still? How is this? I thought it would have to be kept constantly moving to keep it from freezing.

[spingears]

@A.R. Cane

I used to teach the “Principles of Steam Generation” many years ago. Yes there is an endpoint, but I don’t recall what it is. I think it’s around 1300 degrees fahrenheit, but that’s a dim memory and I’m not going to guarantee it.

K&K’s TPOS says that the critical point for water is 3206.2 psia and the corresponding temperature is 705.4 deg.F or 1,165.07 deg.R.
Raising the temperature will effect no change in the vapors.
Nor will increasing the pressure liquify any of the vapors.

[Telemark]

@CookingWithGas

Still? How is this? I thought it would have to be kept constantly moving to keep it from freezing.

IIRC, like bubbles, ice crystals need some irregularity to start forming. If the water has no motion, no ice crystals form and you can get it lower than 32 degrees.

[Chronos]

You also need a very smooth, clean container to superheat or supercool water, since a speck of dust or a scratch in the side can provide a nucleation site to get things started.

[A.R.Cane]

@spingears

K&K’s TPOS says that the critical point for water is 3206.2 psia and the corresponding temperature is 705.4 deg.F or 1,165.07 deg.R.
Raising the temperature will effect no change in the vapors.
Nor will increasing the pressure liquify any of the vapors.

Thanks. That sounds about right. It’s been 40 years so I probably should have refrained from mentioning any specific numbers. That wasn’t part of my curriculum, but I always had some smartassed students who would try to show me up, so I tried to be prepared for them.

[Smeghead]

For the love of…YES! Buy a new thermometer!

[copperwindow]

@flight

More liekly the thermometer was just resting on the bottom of the pot.

Will this raise the tempature?

[asterion]

@copperwindow

Will this raise the tempature?

Yep. You have it right on the metal, which is going to be hotter than the water itself. It can be a pretty impressive difference. The water’s not any hotter at the bottom of the pot, but the bottom of the pot is hotter and that’s what the thermometer is really reporting.

[Annie-Xmas]

Unca Cecil’s take on superheating

[Eleusis]

@Mangetout

Am I right in thinking you mean by the graped comment that a planet with higher gravity would typically have higher atmospheric pressure at the surface? Because on a planet with higher gravity and (for whatever reason)little or no atmosphere, water will **not ** boil hotter.

No, I was just backwards for a sec…

Thanks for correcting me again Mangetout… you are in the top five smartest here IMHO.