<P> The vapour pressure of water is the pressure at which water vapour is in thermodynamic equilibrium with its condensed state . At higher pressures water would condense . The water vapour pressure is the partial pressure of water vapour in any gas mixture in equilibrium with solid or liquid water . As for other substances, water vapour pressure is a function of temperature and can be determined with the Clausius--Clapeyron relation . </P> <Table> Vapour pressure of water (0--100 ° C) <Tr> <Th> T, ° C </Th> <Th> T, ° F </Th> <Th> P, kPa </Th> <Th> P, torr </Th> <Th> P, atm </Th> </Tr> <Tr> <Td> 0 </Td> <Td> 32 </Td> <Td> 0.6113 </Td> <Td> 4.5851 </Td> <Td> 0.0060 </Td> </Tr> <Tr> <Td> 5 </Td> <Td> 41 </Td> <Td> 0.8726 </Td> <Td> 6.5450 </Td> <Td> 0.0086 </Td> </Tr> <Tr> <Td> 10 </Td> <Td> 50 </Td> <Td> 1.2281 </Td> <Td> 9.2115 </Td> <Td> 0.0121 </Td> </Tr> <Tr> <Td> 15 </Td> <Td> 59 </Td> <Td> 1.7056 </Td> <Td> 12.7931 </Td> <Td> 0.0168 </Td> </Tr> <Tr> <Td> 20 </Td> <Td> 68 </Td> <Td> 2.3388 </Td> <Td> 17.5424 </Td> <Td> 0.0231 </Td> </Tr> <Tr> <Td> 25 </Td> <Td> 77 </Td> <Td> 3.1690 </Td> <Td> 23.7695 </Td> <Td> 0.0313 </Td> </Tr> <Tr> <Td> 30 </Td> <Td> 86 </Td> <Td> 4.2455 </Td> <Td> 31.8439 </Td> <Td> 0.0419 </Td> </Tr> <Tr> <Td> 35 </Td> <Td> 95 </Td> <Td> 5.6267 </Td> <Td> 42.2037 </Td> <Td> 0.0555 </Td> </Tr> <Tr> <Td> 40 </Td> <Td> 104 </Td> <Td> 7.3814 </Td> <Td> 55.3651 </Td> <Td> 0.0728 </Td> </Tr> <Tr> <Td> 45 </Td> <Td> 113 </Td> <Td> 9.5898 </Td> <Td> 71.9294 </Td> <Td> 0.0946 </Td> </Tr> <Tr> <Td> 50 </Td> <Td> 122 </Td> <Td> 12.3440 </Td> <Td> 92.5876 </Td> <Td> 0.1218 </Td> </Tr> <Tr> <Td> 55 </Td> <Td> 131 </Td> <Td> 15.7520 </Td> <Td> 118.1497 </Td> <Td> 0.1555 </Td> </Tr> <Tr> <Td> 60 </Td> <Td> 140 </Td> <Td> 19.9320 </Td> <Td> 149.5023 </Td> <Td> 0.1967 </Td> </Tr> <Tr> <Td> 65 </Td> <Td> 149 </Td> <Td> 25.0220 </Td> <Td> 187.6804 </Td> <Td> 0.2469 </Td> </Tr> <Tr> <Td> 70 </Td> <Td> 158 </Td> <Td> 31.1760 </Td> <Td> 233.8392 </Td> <Td> 0.3077 </Td> </Tr> <Tr> <Td> 75 </Td> <Td> 167 </Td> <Td> 38.5630 </Td> <Td> 289.2463 </Td> <Td> 0.3806 </Td> </Tr> <Tr> <Td> 80 </Td> <Td> 176 </Td> <Td> 47.3730 </Td> <Td> 355.3267 </Td> <Td> 0.4675 </Td> </Tr> <Tr> <Td> 85 </Td> <Td> 185 </Td> <Td> 57.8150 </Td> <Td> 433.6482 </Td> <Td> 0.5706 </Td> </Tr> <Tr> <Td> 90 </Td> <Td> 194 </Td> <Td> 70.1170 </Td> <Td> 525.9208 </Td> <Td> 0.6920 </Td> </Tr> <Tr> <Td> 95 </Td> <Td> 203 </Td> <Td> 84.5290 </Td> <Td> 634.0196 </Td> <Td> 0.8342 </Td> </Tr> <Tr> <Td> 100 </Td> <Td> 212 </Td> <Td> 101.3200 </Td> <Td> 759.9625 </Td> <Td> 1.0000 </Td> </Tr> </Table> <Tr> <Th> T, ° C </Th> <Th> T, ° F </Th> <Th> P, kPa </Th> <Th> P, torr </Th> <Th> P, atm </Th> </Tr>

Vapor pressure of water at 20 c kpa