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In simple words, we can say that the partial pressure of a gas in vapour phase is directly proportional to the mole fraction of a gas in solution. An example where Henry's law is at play is the depth-dependent dissolution of oxygen and nitrogen in the blood of underwater divers that changes during decompression , going to decompression sickness .
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]
According to the American Meteorological Society Glossary of Meteorology, saturation vapor pressure properly refers to the equilibrium vapor pressure of water above a flat surface of liquid water or solid ice, and is a function only of temperature and whether the condensed phase is liquid or solid. [17]
Raoult's law (/ ˈ r ɑː uː l z / law) is a relation of physical chemistry, with implications in thermodynamics.Proposed by French chemist François-Marie Raoult in 1887, [1] [2] it states that the partial pressure of each component of an ideal mixture of liquids is equal to the vapor pressure of the pure component (liquid or solid) multiplied by its mole fraction in the mixture.
e * is the saturation water vapor pressure T is the absolute air temperature in kelvins T st is the steam-point (i.e. boiling point at 1 atm.) temperature (373.15 K) e * st is e * at the steam-point pressure (1 atm = 1013.25 hPa) Similarly, the correlation for the saturation water vapor pressure over ice is:
The Clausius–Clapeyron equation [8]: 509 applies to vaporization of liquids where vapor follows ideal gas law using the ideal gas constant and liquid volume is neglected as being much smaller than vapor volume V. It is often used to calculate vapor pressure of a liquid. [9]
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).
The partial pressures obey Dalton's law: =, where P is the total pressure and y i is the mole fraction of the component (so the partial pressures add up to the total pressure). The fugacities commonly obey a similar law called the Lewis and Randall rule: f i = y i f i ∗ , {\displaystyle f_{i}=y_{i}f_{i}^{*},} where f *