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Styrofoam cup in pressure cooker

  1. Jul 27, 2014 #1
    Hello.
    If you give a styrofoam cup to pressure cooker, it expand first, but than it extremly reduce. It reduce because the high pressure of the water vapor within the pressure cooker compresses or squeezes the tiny air pockets within the styrofoam cup and reduces the size of the cup, ok.
    But why it expand first? And why it will melt, if you leave it in the pressure cooker too long?

    Thank you very much.
     
  2. jcsd
  3. Jul 27, 2014 #2
    What happens with the air in the tiny air pockets as its temperature rises? What happens with the stuff in which the tiny air pockets exist along that way?
     
  4. Jul 27, 2014 #3

    davenn

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    its really hot in the pressure cooker and Styrofoam has a very low melting point :smile:

    Dave
     
  5. Jul 27, 2014 #4
    The air in air pockets have bigger pressure, so it can make cup expand. But why it reduce than?
     
  6. Jul 27, 2014 #5

    davenn

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    so what do you think happens when the air pocket bubbles burst ?



    Dave
     
  7. Jul 28, 2014 #6
    So, the cup will be reduce. Buw why the air bubless burst?
     
  8. Jul 29, 2014 #7

    davenn

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    think about what is happening to the air in the bubbles as it heats up

    when you answer that question you will have the answer to the bursting bubbles :smile:


    Dave
     
  9. Jul 29, 2014 #8
    The bubble has bigger pressure and if it can, it expand. But in one while it can not expand. So, it burst? It is like a soap bubble? And where will go the air from the bursted bubbles? To the cooker?
     
  10. Jul 29, 2014 #9

    davenn

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    yes, will mix into the air in the cooker
    so lots of bubbles expanding and bursting release their little bits of air and the remaining Styrofoam collapses and its area decreases in size :smile:

    Dave
     
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