The Enhancement of Water Vapor in Carbon Dioxide-Free Air at 30, 40, and 50 °C
Richard W Hyland1, Arnold Wexler1
1Institute for Basic Standards, National Bureau of Standards, Washington, D.C. 20234.
Abstract:
The enhancement of water vapor in compressed atmospheric air was measured at 30, 40, and 50 °C over respective pressure ranges of 10 to 35 bars, 15 to 60 bars, and 10 to 100 bars. The data for each isotherm were fitted by the method of least squares to an empirical smoothing equation of the form ln f = a + bP where f is the enhancement factor, P is the total (absolute) pressure and a and b are constants. A detailed error analysis, necessary for the eventual use of the data in humidity standards work, shows that the calculated (predicted) values of f have an estimated limit of systematic bias of ±0.07 percent and a maximum observed standard deviation of a predicted value of ±0.2 percent.
Related Concept Videos
02:35Clausius-Clapeyron Equation
02:44Heating and Cooling Curves
For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...
03:12Freezing Point Depression and Boiling Point Elevation
The boiling point of a liquid is the temperature at which its vapor pressure is equal to ambient atmospheric pressure. Since the vapor pressure of a solution is lowered due to the presence of nonvolatile solutes, it stands to reason that the solution’s boiling point will subsequently be increased. Vapor pressure increases with temperature, and so a solution will require a higher temperature than will pure solvent to achieve any given vapor pressure, including one...
02:39Phase Diagrams
02:11Effects of Temperature on Free Energy
03:28Vapor Pressure Lowering