The boiling point of water is 100 °C (212 °F) at standard pressure. I have always assumed that this is the hottest water can get before evaporating, but my buddy says that it is possible to get water hotter than that (in a microwave, for instance).
Is this true? If so, why?
2007-10-31 11:40:12 · 8 answers · asked by jason 1 in Science & Mathematics ➔ Other - Science
Of course water can be heated to a point much greater than its boiling point. Not only can it be excessively heated in a microwave, but in a pressure cooker as well. In the case of the pressure cooker the water won't boil at 212F because of the pressure exerted on the water surface. Conversely, water heated on a mountain top will boil at a lower temperature because of the lower atmospheric pressure. Microwave heated water will excite the water molecules to such a rapid rate that the water can not maintain a steady 212 thru the boiling process. In addition, if the vessel in the microwave is perfectly smooth (or nearly so) there won't be any place for the bubbles to form. The result would be an eruption of the water out of the vessel, but the water temperature would be far above 212.
2007-10-31 11:54:42 · answer #1 · answered by abono11746 4 · 0⤊ 0⤋
I believe you are talking about superheated water. Yes, it CAN be heated substantially above 100 deg. C at standard pressure. You can also supercool water below 0 deg. C without freezing it.
The key issue here is the nucleation of the bubbles that are formed in the boiling process. A particle or bit of dirt is where the bubble starts to form. If the water container is smooth and very clean, and the water is super clean then there is no place for the bubble to form & the water super heats.
This is well known to chemists who commonly have "boiling chips" available. Since they usually use super clean water and flasks, they need to prevent superheating so they throw a few boiling chips into the flask. These chips are essentially "clean" dirt & create spots for the bubbles to form.
Oh yeah, you can raise the boiling point above 100 C by pressurizing it. But then it will still boil at its boiling point, if there are dirt particles available, even if the boiling point is now 150 deg. C.
2007-11-03 22:35:59 · answer #2 · answered by Tom H 4 · 0⤊ 0⤋
The volume of water being heated will play a factor, as the more there is, the longer you will have to heat it, and quite possibly it will get hotter than that. Any water heated above it's boiling point at STANDARD pressure will begin to boil and evaporate, but at higher pressures it will need to be heated to a higher temp.
2007-10-31 18:52:16 · answer #3 · answered by Anonymous · 0⤊ 0⤋
No, not at standard pressure. It might be that the container is getting hotter and that is what is being measured.
Water conducts heat so well that it is possible to boil water in a paper container over a Bunsen burner without burning the paper. Any local spot that gets over 212 turns to steam and dissipates the heat
2007-10-31 18:50:18 · answer #4 · answered by Mike1942f 7 · 0⤊ 0⤋
Once water gets hotter then that, you are correct in that it will start to evaporate, even in the microwave. All the water won't evaporate right away (unless it's super heated, like when you drop droplets of water on a hot pan, it evaporates right away), so you might get fluctuations in the readings and get a higher temp. Volume is a factor in this question.
2007-10-31 18:48:02 · answer #5 · answered by Malina 7 · 0⤊ 1⤋
Yes in a pressure cooker. The boiling point is 212F at sea level.If you increase the pressure in a confined space, the boiling point goes up and the water gets hotter.. That is why pressure cookers cook more quickly than regular cookware.
2007-10-31 20:29:15 · answer #6 · answered by Renaissance Man 5 · 0⤊ 0⤋
Dissolve something in it. That raises the boiling point.
2007-10-31 22:19:11 · answer #7 · answered by Anonymous · 0⤊ 0⤋
answered here.
2007-10-31 18:49:20 · answer #8 · answered by Ṣaḥābah . 5 · 0⤊ 1⤋