Boiling point of water...?

Question

Given that water (pure?) boils at 212 degrees Fahrenheit at sea level (standard atmospheric conditions?) is there a standard for the decrease in boiling point with each (1,000 ft) increase in altiutde? I live at 7,150 feet (+ or -) and an ordinary kitchen cooking thermometer shows the water boiling at 198 degrees. If you could take a quantity of water continually higher, at what point in elevation would the water "boil" off without an application of heat/energy to it?

Answer 1

Because it sounds like you want a detailed answer.
Boiling occurs when the vapor pressure of water, the pressure that gaseous water exerts at a temperature, is greater than the atmospheric pressure. The vapor pressure is dependent on temperature, so decreasing the temperature that the water boils at will decrease the vapor pressure. Also, decreasing the atmospheric pressure will result in the vapor pressure overcoming the atmospheric pressure at a lower temperature because there is less to overcome. Therefore its about finding the balance between the vapor pressure and atmospheric pressure at a particular temperature.

If your still up for a more detailed answer.
The vapor pressure for water as a function of temperature is given by the goff gratch equation. You can look that up on wikipedia if you really want.
and you can go here
http://en.wikipedia.org/wiki/Atmospheric_pressure
to find an explanation of atmospheric_pressure as a function of height.
remember at boiling atmospheric pressure = vapor pressure.
set the two equations equal to each other and you can solve for hieght vs temperature.

Answer 2

  Sadly the answer is just No. Water will not just boil as any other liquid.
  Some other liquids will just boil (with a small temperature) when taken to outer space. But water molecules have Strong Hydrogen bonds to keep them together. That is why water has such a high boiling point (that is too high for its molecular mass). It is that molecules with higher molecular mass boil at lower temperatures and vice versa.
  This wonderful hydrogen bond is the very reason for the life on earth. Without that all water will boil and steam on atmospheric temperature.
  Apart from hydrogen bonds there are many other factors like VanderWaals bonds. Sadly you cannot apply vapour pressure since it is used for closed systems. The outer space is not a closed system...
  When you say without application of heat energy, we can’t apply that. A substance needs energy for its molecules to jump away from the rest. The Kelvin zero is considered as the lowest possible temperature. When you take something outer space it can get heat energy from things far away from radiation, light of stars &c. You cannot cool anything to Kelvin zero where even air will freeze. It is hypothetical.

Answer 3

Because of the lower boiling point of water at high altitude, there is an approximate decrease of 2 degrees for every increase of 1000 feet in elevation.

Answer 4

There is an approximation of change in B.Pt. with height, but this only applies at low altitudes. If you went up to 20,000 metres (= 66,000ft) the air pressure would be about 55hPa (that's only about 5% of air pressure at sea level) at which point water boils at about 30 deg C = 86 deg F.

Answer 5

Outer space is the nearest one can get to Absolute Zero pressure... -14.7psi, 0mmHg.

As the boiling point of water decreases with decreasing pressure, (I know that at 3"Hg absolute, water boils at 150°F).

I believe that, at near absolute zero pressure, water will boil due to its own heat of molecular activity.

Answer 6

Changing the subject, this is the only way I could let you know somenthing. I'm the guy that wrote the "gear-head" question, and your answer was a great explanation, and in 24 hours, you're going to get Best Answer.

Answer 7

in outer space where there's no atmospheric pressure, all boiling points of liquids decrease. in the vacuum of outer space, any liquid will boil at any temperature

Answer 8

i think water will just evaporate not boil.

Answer 9

I agree cal_sil.