# Temp of co2 under pressure

1. Jun 3, 2006

### rikpotts

Hi,

Can someone help me find out what happens to temp of co2 when under pressure? Its hard for me to throw any quantities at this so I am kind of guessing up a scenario.!

Say you have a a steel box of 1m^3 and fill it with co2 (which is 20'c) to a pressure of say 4 bar and then put this box in a room of constant 20'c.

Will the co2 eventually reach 20c? Will the temp of the co2 under pressure initially be above or below 20'c? Does the co2 only get much colder when it is released from the pressurized container?

Hope someone can help! I really should know this but have sent myself dizzy thinking about it.

Many Thanks
Rik

2. Jun 3, 2006

### Integral

Staff Emeritus
Yes, the CO2 will reach an equilibrium temperature equal to its surroundings.

Edit:
You do not provide enough information to answer questions about the initial temperature

Last edited: Jun 3, 2006
3. Jun 7, 2006

### wywong

At the beginning the CO2 expands against the surrounding air. So it loses some mechanical energy (and the air gains some). This 'adiabatic expansion' results in a temperature drop. I don't have the physical constants on hand to estimate the drop. I would say it will be a few degrees C. At the same time the air warms a bit (but to a lesser degree because more air is involved). In a matter of seconds, the gases are thoroughly mixed and the resultant temp will be 20C.

Wai Wong