Water boils when it's vapor pressure equals atmospheric pressure (i.e., 760 mm of Hg) which is at 100 degrees Celsius. If the temperature is further increased, would the vapor pressure also increase or remain same?

  • $\begingroup$ Vapor pressure surely would increase, as long as you still have liquid water around. $\endgroup$ – Ivan Neretin Jun 6 '17 at 11:29
  • $\begingroup$ Do you mean to ask what is the vapor pressure within the system during the phase transition? Or are you asking what happens as the temperature is increased after boiling is complete? $\endgroup$ – J. Ari Jun 6 '17 at 12:42
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    $\begingroup$ Steam tables are a forgotten art form. There is a reason for the development of super-heat for steam locomotives. $\endgroup$ – Jon Custer Jun 6 '17 at 13:02

Your question is phrased inconsistently. As you noted under "normal conditions", water boils at 100 degrees Celsius when the pressure is 760 mm of Hg. At that point there is no liquid water left and hence, technically, there is no liquid water to have a "vapor pressure."

Now steam (gaseous water) can have a pressure above atmospheric pressure if heated above 100 degrees Celsius in a closed container. (as Jon Custer has commented...)


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