# Would Co2 be liquid or gas?

1. Oct 6, 2014

### willstaruss22

Let's say you have a 20 bar atmosphere of 95% nitrogen, 3% oxygen, 1% argon and 1% Co2 cooled to 0 F. Would Co2 be liquid or gas?

2. Oct 6, 2014

### SteamKing

Staff Emeritus
Get yourself a CO2 phase diagram and see.

3. Oct 6, 2014

### willstaruss22

The partial pressure is 0.2 bar so it would be gas. However with the whole atmosphere is would be liquid.

4. Oct 6, 2014

### Staff: Mentor

The vapor pressure of co2 at 0F is about 20 bars, and the partial pressure of the co2 in your gas mixture is about 1 bar. So it won't condense.

Chet

5. Oct 7, 2014

### willstaruss22

Here's where I'm confused is it the partial pressure of Co2 that determines which state its in or the total atmosphere? Because if in this scenario the temperature were -40 F Co2 would be liquid with the total atmosphere but it would be gas at partial pressure.

6. Oct 7, 2014

### Staff: Mentor

It's the partial pressure that matters, not the total pressure.

Chet

7. Oct 7, 2014

### epenguin

Which would you think it should be? It is nice to be told a confirmation, but it is not that much help to you really if you can't or don't reason it out mechanistically.