The Naked Scientists

The Naked Scientists Forum

Author Topic: Can I lower temperature by reducing volume?  (Read 1888 times)

Offline Liskow

  • First timers
  • *
  • Posts: 1
    • View Profile
Can I lower temperature by reducing volume?
« on: 13/03/2009 17:26:10 »
Hot things tend to be a little larger than cold things.  So can I lower a things temperature by squishing it into a smaller volume?

Mod edit - Please make your subjects as the question you wish to ask.  This makes the forum tidier and easier to navigate, Thanks!
« Last Edit: 16/03/2009 09:46:34 by BenV »


 

Offline lancenti

  • Full Member
  • ***
  • Posts: 96
    • View Profile
Re: Can I lower temperature by reducing volume?
« Reply #1 on: 13/03/2009 18:05:12 »
This is not necessarily true.

Unit mass of water at 4 degrees centigrade has a smaller volume than unit mass of water at 1 degree centigrade, if I remember right. Water is densest at 4 degrees I believe.

However, using the ideal gas law,

pV=nRT

or Charles Law (I believe)

V1/T1=V2/T2

We find that compression should actually lead to an increase in temperature. Hence to cool a gas, you'd probably want to rapidly expand it.
 

blakestyger

  • Guest
Re: Can I lower temperature by reducing volume?
« Reply #2 on: 13/03/2009 18:37:45 »
We find that compression should actually lead to an increase in temperature. Hence to cool a gas, you'd probably want to rapidly expand it.

Yep - the Joule-Thompson effect.
 

Offline lightarrow

  • Neilep Level Member
  • ******
  • Posts: 4586
  • Thanked: 7 times
    • View Profile
Re: Can I lower temperature by reducing volume?
« Reply #3 on: 14/03/2009 10:55:24 »
Hot things tend to be a little larger than cold things.  So can I lower a things temperature by squishing it into a smaller volume?
Even if your first sentence were always true (but it's not) it's wrongly stated:
when you *give heat* to things they enlarge. Infact, if you compress them, you *receive heat* from them.
« Last Edit: 14/03/2009 10:59:39 by lightarrow »
 

Offline Raghavendra

  • Hero Member
  • *****
  • Posts: 835
  • Quantum
    • View Profile
    • Raghavendra
Re: Can I lower temperature by reducing volume?
« Reply #4 on: 16/03/2009 09:36:59 »
hmmm you are at critical

          You should read raoult's law
 

The Naked Scientists Forum

Re: Can I lower temperature by reducing volume?
« Reply #4 on: 16/03/2009 09:36:59 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums