[ACMAir]

Hi. This is my first post on this forum. What gas's pressure changes most dramatically with a change in temperature?

[Borek]

Depending on the context it is either a trick question, or very subtle one. What are you learning about now?

[ACMAir]

It isn't in context. Its a question based on curiosity. For instance, if oxygen was heated by 1 degree celsius, what would be its change in pressure. Isn't this Boyles, Charles, or someone like that's law?

[Borek]

At first approximation for a given sample of gas in constant volume p/T=const regardless of gas type. This is so called Gay-Lussac's law (you were close, but missed).

[ACMAir]

Oh, so its not something that is specific to a certain gas, rather a universal number?

[Borek]

To some extent. Trick is, all gas laws (together with so called combined gas law) work OK for ideal gases - and every real gas slightly deviates from ideal behavior. The lower the temperature, the higher the pressure, the higher the deviation.

[ACMAir]

The lower the temperature, the higher the pressure, the higher the deviation.

Isn't is the higher the temperature the higher the pressure? Since, atoms are excited at higher temperatures and push against the walls of their container with greater force?

[Borek]

You are right, but that's not what I am referring to. What I meant was that the difference between real and ideal gas behavior becomes higher for high pressures and low temperatures. Gas at 0.1 atm and 300 °C is very close to ideal, gas at 100 atm and -200 °C is far from ideal (if it is not already liquid).

[ACMAir]

You are right, but that's not what I am referring to. What I meant was that the difference between real and ideal gas behavior becomes higher for high pressures and low temperatures. Gas at 0.1 atm and 300 °C is very close to ideal, gas at 100 atm and -200 °C is far from ideal (if it is not already liquid).

Oh ok, thanks a lot Borek