Vapour pressure of water
From Infogalactic: the planetary knowledge core
The vapor pressure of water is the pressure at which water vapor is in thermodynamic equilibrium with its condensed state. At higher pressures water would condense. The water vapor pressure is the partial pressure of water vapor in any gas mixture in equilibrium with solid or liquid water. As for other substances, water vapor pressure is a function of temperature and can be determined with Clausius–Clapeyron relation.
T, °C | T, °F | P, kPa | P, torr | P, atm |
---|---|---|---|---|
0 | 32 | 0.6113 | 4.5851 | 0.0060 |
5 | 41 | 0.8726 | 6.5450 | 0.0086 |
10 | 50 | 1.2281 | 9.2115 | 0.0121 |
15 | 59 | 1.7056 | 12.7931 | 0.0168 |
20 | 68 | 2.3388 | 17.5424 | 0.0231 |
25 | 77 | 3.1690 | 23.7695 | 0.0313 |
30 | 86 | 4.2455 | 31.8439 | 0.0419 |
35 | 95 | 5.6267 | 42.2037 | 0.0555 |
40 | 104 | 7.3814 | 55.3651 | 0.0728 |
45 | 113 | 9.5898 | 71.9294 | 0.0946 |
50 | 122 | 12.3440 | 92.5876 | 0.1218 |
55 | 131 | 15.7520 | 118.1497 | 0.1555 |
60 | 140 | 19.9320 | 149.5023 | 0.1967 |
65 | 149 | 25.0220 | 187.6804 | 0.2469 |
70 | 158 | 31.1760 | 233.8392 | 0.3077 |
75 | 167 | 38.5630 | 289.2463 | 0.3806 |
80 | 176 | 47.3730 | 355.3267 | 0.4675 |
85 | 185 | 57.8150 | 433.6482 | 0.5706 |
90 | 194 | 70.1170 | 525.9208 | 0.6920 |
95 | 203 | 84.5290 | 634.0196 | 0.8342 |
100 | 212 | 101.3200 | 759.9625 | 1.0000 |
Contents
Approximation formula
The vapor pressure of water may be approximated by the following relations (in order of increasing accuracy):
- Using the Antoine equation
-
- where the temperature T is in degrees Celsius and the vapor pressure P is in mmHg. The constants are given as
-
A B C Tmin, °C Tmax, °C 8.07131 1730.63 233.426 1 99 8.14019 1810.94 244.485 100 374
Graphical pressure dependency on temperature
See also
References
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Further reading
- Lua error in package.lua at line 80: module 'strict' not found.
- Murphy, D. M. and Koop, T. (2005): Review of the vapour pressures of ice and supercooled water for atmospheric applications, Quarterly Journal of the Royal Meteorological Society 131(608): 1539–1565. doi:10.1256/qj.04.94