Search results
Results from the WOW.Com Content Network
Values are given in terms of temperature necessary to reach the specified pressure. Valid results within the quoted ranges from most equations are included in the table for comparison. A conversion factor is included into the original first coefficients of the equations to provide the pressure in pascals (CR2: 5.006, SMI: -0.875).
At the normal boiling point of a liquid, the vapor pressure is equal to the standard atmospheric pressure defined as 1 atmosphere, [1] 760 Torr, 101.325 kPa, or 14.69595 psi. For example, at any given temperature, methyl chloride has the highest vapor pressure of any of the liquids in the chart.
The boiling point of water is the temperature at which the saturated vapor pressure equals the ambient pressure. Water supercooled below its normal freezing point has a higher vapor pressure than that of ice at the same temperature and is, thus, unstable. Calculations of the (saturation) vapor pressure of water are commonly used in meteorology.
The torr (symbol: Torr) is a unit of pressure based on an absolute scale, defined as exactly 1 / 760 of a standard atmosphere (101325 Pa). Thus one torr is exactly 101325 / 760 pascals (≈ 133.32 Pa).
English: Plot of water vapor pressure p in Torr (mmHg) and hPa versus Temperature T in degrees Celsius. Note that the vapor pressure equals atmospheric pressure (760 Torr) at the boiling temperature of water. Produced by Yannick Trottier in 2006. Extended by Dr. Schorsch (talk) 10:32, 25 April 2021 (UTC).
Phase behavior Triple point: 184.9 K (−88.2 °C), ? Pa Critical point: 508.7 K (235.6 °C), 5370 kPa Std enthalpy change of fusion, Δ fus H o: 5.28 kJ/mol Std entropy change
where temperature T is in degrees Celsius (°C) and saturation vapor pressure P is in kilopascals (kPa). According to Monteith and Unsworth, "Values of saturation vapour pressure from Tetens' formula are within 1 Pa of exact values up to 35 °C." Murray (1967) provides Tetens' equation for temperatures below 0 °C: [3]
Note that the form of this formula as given is a fit to the Clausius–Clapeyron equation, which is a good theoretical starting point for calculating saturation vapor pressures: log 10 (P) = −(0.05223) a / T + b , where P is in mmHg, T is in kelvins, a = 38324, and b = 8.8017.