Theoretically, could a gas be denser than a liquid (ie of a different substance)? Does such a combination actually exist, and if so at a common temperature and pressure?

  • $\begingroup$ liquid hydrogen is 0.07, or 70 kg/cubic meter. Tungsten hexafluoride gas is 13 kg/cubic meter, so there is gap. Note that solid aerogel is a mere 1.9 kg/cubic meter. $\endgroup$
    – JEB
    Sep 23 '18 at 1:00
  • $\begingroup$ I think the problem with your question is that there is not a clear-cut distinction between a gas and a liquid in general. By varying the temperature and pressure of water, for example, one can continuously go from water in liquid form to water in gas form. At near the critical point (P=220 atm and T=374 ˚C for water), the density difference between water on the 'gas' side of the liquid-gas phase line and water on the 'liquid' side becomes infinitesimally small. Is water near its critical point on the 'gas' side of the phase line denser than some liquid? Almost certainly, yes. $\endgroup$
    – user93237
    Sep 23 '18 at 7:37
  • $\begingroup$ -1 No research effort. Please take note of Related Questions which are suggested when posting your question, to check that it has not already been answered. $\endgroup$ Sep 23 '18 at 9:55

Since boiling points and melting points are given as constants at a given temperature since they vary with temperature and pressure, I would assume that in most cases for the pressure to be high enough for density to increase to the same levels as a liquid that it would also force a change of state, unless the temperature was higher such that particles had enough kinetic energy to not be affected by the attractive forces?

  • 1
    $\begingroup$ Not clear what you are saying. Try splitting into 2 or more simpler sentences. Is this an answer or a comment? Why the question mark? $\endgroup$ Sep 23 '18 at 9:52

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