Can someone please explain to me how water can be 350 degrees?

[rudeguy]

I thought it turned to steam at 212 degrees?

 

[coxmaster]

I thought it turned to steam at 212 degrees?

It (depending on the circumstances) begins to boil at 212ºF


A superheated liquid can go well above the standard boiling point

 

[geno]

If it's under enough pressure, it increases the boiling point.

Link

 

[tatteredpotato]

I think supercool water is.... well cooler

http://axiomsun.com/home/video/supercooled_water.html

 

[Sukhoi]

I thought it turned to steam at 212 degrees?

Steam is water.

 

[dainthomas]

Steam is water.

Haha, stole my post!

 

[a123456]

If it's under enough pressure, it increases the boiling point.

Link

This. Pressurized water has a higher boiling point. It's how nuclear reactors work. Water in PWRs can be liquid up to 700+ degrees because the pressure is 150+ atm.

Boiling point is also affected by substances that are dissolved in the water and also by the external vapor pressure (i.e. altitude where your are boiling the water).

 

[Fritzo]

If it's under enough pressure, it increases the boiling point.

Link

Yep. Under pressure, water doesn't go critical until 374F.

 

[FuzzyDunlop]

Not only pressure can cause water to heat about 212 without boiling.

Years ago I remember seeing news feature on TV about how some lady stuck a spoon into water she heated in the microwave and the water literally exploded into her face. How this happened was that the vessel she was heating the water in (the cup) had a completely smooth bottom. This completely smooth bottom didnt have the indentations and imperfections needed for the water to form bubbles once 212 degrees was reached. Due to the lack of bubble formation, actual boiling never took place, but as soon as she broke the surface of the water with the spoon, the bubbles instantly formed around it, causing the water to burst into her face, scalding her.
Pretty intense.
http://www.snopes.com/science/microwave.asp

 

[rcpratt]

This. Pressurized water has a higher boiling point. It's how nuclear reactors work. Water in PWRs can be liquid up to 700+ degrees because the pressure is 150+ atm.

Boiling point is also affected by substances that are dissolved in the water and also by the external vapor pressure (i.e. altitude where your are boiling the water).

Generally only 600F or so, need some margin. But yeah, BP at ~150atm is ~700F.

 

[DrPizza]

Not only pressure can cause water to heat about 212 without boiling.

Years ago I remember seeing news feature on TV about how some lady stuck a spoon into water she heated in the microwave and the water literally exploded into her face. How this happened was that the vessel she was heating the water in (the cup) had a completely smooth bottom. This completely smooth bottom didnt have the indentations and imperfections needed for the water to form bubbles once 212 degrees was reached. Due to the lack of bubble formation, actual boiling never took place, but as soon as she broke the surface of the water with the spoon, the bubbles instantly formed around it, causing the water to burst into her face, scalding her.
Pretty intense.
http://www.snopes.com/science/microwave.asp

You could repeat that experiment 1000 times and odds are, it wouldn't happen again. However, if you heated the water once in the microwave, allowed it to cool, then heated it again, the odds significantly increase of that happening.

 

[Hacp]

Google the phase diagram for water.

 

[OutHouse]

You could repeat that experiment 1000 times and odds are, it wouldn't happen again. However, if you heated the water once in the microwave, allowed it to cool, then heated it again, the odds significantly increase of that happening.

why?

 

[LordMorpheus]

Yep. Under pressure, water doesn't go critical until 374F.

at some pressure that's true. The boiling point is a function of pressure - the more pressurized your system is, the higher the boiling point.

Try taking the cap off your radiator when everything is still warm - the sudden decrease to atmospheric pressure means all that water in your engine is suddenly hotter than boiling and it will begin to vaporize until it cools (mostly by having the vaporization suck up energy) down below 212.

 

[Drako]

PV = nRT

 

[rcpratt]

PV = nRT

...not really.

 

[KK]

why?

it doubles the chances.

 

[Drako]

...not really.

LOL, I knew I failed chemistry for a reason

 

[tcsenter]

OP never took junior high chemistry?

 

[Matthiasa]

Distilled deionized water also does dumb things.

 

[zinfamous]

Autoclave?

 

[Eli]

why?

Because it reduces the number of possible nucleation sites.

Same principle as creating rain. There is supercooled water in the atmosphere, it just needs a trigger. In the case of creating rain, that trigger is silver iodide, which happens to have a similar molecular structure to frozen water. This creates sites where ice can nucleate.

In the case of boiling water, a bubble of air is the nucleation site. If you remove all of the air trapped in the water by first boiling it, the chances of you being able to superheat the water are greatly increased.

This phenomenon can also be seen with bottled liquid products. Have you ever pulled a bottle of water out of the fridge, only to have it literally freeze as it's going down your throat? lol

 

[lupi]

this a serious question?

 

[rudeguy]

Steam is water.

I don't like you...


The thing that got me thinking about this was an episode of Modern Marvels. They were making huge dump truck tires and were pouring 350 degree water on the rubber to get some chemical reaction to happen. It indeed was under pressure. I never knew that pressure upped the boiling point like that.

Thanks for increasing my ever decreasing knowledge ATOT!

 

[rudeguy]

this a serious question?

yep

If I'm curious about something, I ask. I'm not afraid to admit that there are a lot of things I don't understand in the world.