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Vapor Pressure of Water at Various Temperatures


The apparatus is fragile and filled with mercury, please handle it gently.


  • Vapor pressure of water apparatus
  • Hot plates
  • Two 4 liter beakers
  • Meter stick


  1. About 1 hour before classtime, 2/3 fill one beaker with water and heat the water on a hot plate.
  2. Place the other empty beaker on another hotplate and then clamp the vapor pressure of water apparatus so that it is suspended inside the beaker. Make sure the hotplate is OFF.
  3. Show students the vapor pressure of water at room temperature.
  4. Then pour the previously heated water into the vessel containing the apparatus.
  5. Again measure the vapor pressure and temperature. The water can be heated further by turning on the hotplate.


Vapor pressure of water (mm Hg) Temperature (ºC)
17.5 20
31.8 30
55.3 40
92.3 50
147 60
233 70
355 80
526 90
760 100