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Vapor pressure formulation for water in range 0 to 100 C. A revision

1976; The National Institute of Standards and Technology; Volume: 80A; Issue: 5 and 6 Linguagem: Inglês

10.6028/jres.080a.071

2376-5704

Arnold Wexler,

Advanced Thermodynamics and Statistical Mechanics

In 1971 Wexl er and Greenspan p ublished a formulation for the vapor pressure of water encompassing the temperatu re ran ge 0 t o 100°C.In this paper a revision is m ad e of tha t earli er formulati on t o m a ke it consist ent with the defin itive experimental va lue of the vapor pre sure of ,mter at it s trip le po int recently obtained b y Gu ildn er, J ohnson, and J ones .The two formula t ions a re essenti a ll y identical at t emperatures from 25 to 100 °C.F or t emperatures below 25 °C the new formul at ion predicts values that a re higher than the 1971 formul ati on.At the triple point, the vapor press ure given by the new formula ti on is 611.657P a '\'hereas the value given by the 1971 formul a ti on is 611.196P a .A t a ble is given of th e va por pressure as a functi on of t emperature at O.l-deg intervals over the range 0 to 100 °C on th e I n t ernational Prac tica l T emperature Scale of 1968, t ogethe r with values of the temperature d erivati ve a t 1-deg interv als.K eywords : Clap eyron equati on; saturati on vapor pressu re over water ; st eam; vapor pressure ; vapor pressure of wa t er ; virial coe ffic ients.