# CO2 expansion rates

1. Sep 24, 2007

### dsignguy

I need a formula to figure out the expansion of CO2.
Ex: if I'm at sea level, "room temp", I've got 1cubic foot of co2 at 120psi, What is the volume when its released to ambient air ?

Can anyone help?

Shawn

2. Sep 24, 2007

### mgb_phys

Any gas follows a law P V = n R T where P = pressure (pascals) V = volume (m^3), n is the number of moles (44g for CO2), R is a constant 8.3145 J/(mol K) and T is the absolute (kelvin ) temperature.

Alternatively 44g of CO2 occupies 24litres at room temmp/pressure. The volume decreases linearly with pressure and increases linearly with absolute temperature.

3. Sep 24, 2007

### Gokul43201

Staff Emeritus
That's a little confusing. To clarify, n is not 44g (which is the value of the molar mass).

4. Sep 24, 2007

### mgb_phys

Sorry, yes to make it clearer. n is the number of moles, each mole of CO2 weighs 44g.

But you can work it all out from just knowing that P * V is constant so long as temperature doesn't change.