Is water 'supposed' to boil at a lower temperature?

[TheAbsoluTurk]

A biology teacher once said to his class something to the effect of water posessing qualities that it should not. I don't remember what reasons he gave but my notes say that water 'should' exist as a gas at -90 degrees Celsius at 1 bar.

Do any of you know why this is?

 

[Jorriss]

I assume what he meant was that if you model water without taking into hydrogen bonding it has much weaker inter-molecular forces?

 

[TheAbsoluTurk]

I assume what he meant was that if you model water without taking into hydrogen bonding it has much weaker inter-molecular forces?

Does that mean a single atom of water evaporates at a lower temperature than 100 degrees Celsius?

 

[wukunlin]

a single molecule of water can't form liquid or solid

 

[Chestermiller]

Water can evaporate at temperatures below 100C if its partial pressure in the gas phase in less than 1 atm. Just set out a small bowl of water in your kitchen for a few days and see what happens. Water will always evaporate if its partial pressure in the gas phase is less than the equilibrium vapor pressure at the liquid temperature.

Chet

 

[TheAbsoluTurk]

Ok, from what I've read from you guys, water exists as a liquid at a pressure of 1 atm at temperatures of 0 degrees Celsius and 100 degrees Celsius because of hydrogen bonding. That means the individual hydrogen atoms in each H20 are attracted to the oxygen atom of other water molecules, right?

 

[nickbob00]

What he means is that, if you compare water to other molecules of a similar size (ammonia, hydrogen chloride, methane) it has unusually high melting, boiling points and specific heat capacities due to the hydrogen bonding in water.

 

[technician]

Boiling occurs when the vapour pressure equals the atmospheric pressure. Vapour then forms throughout the body of the liquid. Evaporation occurs from the surface of the liquid at all temperatures.