Then, what is the boiling point for water in vaccum condition?

Question

For methanol, what will be the boiling point then? is there any equation i can use to calculate or estimate the B.P?

Answer 1

if there is a perfect vacuum you don't need to boil it using heat! it always boil without heat! since there is no particle in free space water molecules will try to replace the space!

Answer 2

Water under vacuum will boil at lower temperature depending on the vacuum it is under.
At about 16kPa (2.0psia) absolute pressure, water boils at around 55°C (131°F).
At 55kPa (8psia), water boils at 85°C (185°F).

As methanol is a very light alcohol, its boiling point under vacuum will be very much lower than its normal BP of 65°C, again the BP will depend upon the degree of vacuum it is under.

Answer 3

There isn't one. Water has a vapour pressure at any temperature. So whatever the ambient temperature is, once you pump the pressure down to that value, the water boils off. As long as any liquid water remains, you cannot create a perfect vacuum - you find you just keep pumping out water vapour.

Same applies to methanol, though its vapour pressure will generally (always, perhaps?) be higher than for water.

Answer 4

It depends on how much of a vacuum you have.
At a pressure of 7.6x10^-6 inches of mercury, the boiling point of water is -120 Deg.F.