Humidity, relating to the quantity of moisture in atmospheric air, is accurately given by equations derived from the ideal-gas law and Raoult’s law for H₂O.
(a) The absolute humidity h is defined as the mass of water vapor in a unit mass of dry air. Show that it is given by:

where ℳ represents a molar mass and pH₂O is the partial pressure of the water vapor, i.e., pH₂O = ^yH₂O^P .
(b) The saturation humidity h^sat is defined as the value of h when air is in equilibrium with a large body of pure water. Show that it is given by:

where p^satH₂O is the vapor pressure of water at the ambient temperature.
(c) The percentage humidity is defined as the ratio of h to its saturation value, expressed as a percentage. On the other hand, the relative humidity is defined as the ratio of the partial pressure of water vapor in air to its vapor pressure, expressed as a percentage. What is the relation between these two quantities?

Transcribed Image Text:

MHO PH0 h= OH M air P- PH;0