Water vapor at approx. 300 degrees Celsius

  1. Ive heard that at somewhere around 300 degrees Celsius (cant remember the exact number), you cant liquidise it anymore. Is this fact correct?

    Thanks in advance,
    fawk3s
     
  2. jcsd
  3. Dadface

    Dadface 2,084
    Gold Member

    You can liquidise a vapour by applying a high enough pressure but only if the vapour is at a temperature lower than its "critical temperature".If the temperature is higher than the critical temperature then applying pressure results not in a liquid but in a compressed vapour.
     
  4. Thats what I thought. Thanks !
     
  5. This shows up the difficulty with using common terms in science - a supercritical fluid is neither liquid nor gas. (And yet it's both at the same time).

    Is a liquid crystal a solid or a liquid? - Same problem.
     
  6. I'd need to check a book of steam tables but I'm pretty sure that water can still be aliquid at a lot more then 300 Deg C
     
  7. Dadface

    Dadface 2,084
    Gold Member

    I just checked and the critical temperature of water is 374Deg C.
     
  8. Ah, yes, the critical point is 374 degrees C. (The OP did say 'about' 300)
    It's surprisingly low though.
     
  9. K^2

    K^2 2,470
    Science Advisor

    I'm pretty sure what OP heard is a mention of critical point. Sounds like it. Past these 374°C, there is no phase transition from vapor to liquid, and that might come out as "can't liquidise" to someone who didn't quite get the point.
     
Know someone interested in this topic? Share a link to this question via email, Google+, Twitter, or Facebook

Have something to add?