Formula or list needed for gas 'critical temperature' calc

[bitman]

Hi

Is there a formula which predicts at which temperature a gas condenses to a liquid ?. I think its called the critical temperature.

I've found out thay C02 is 31C and Nitrogen -178.

If not a formula can someone point me to a list of gases with info. I'd be quite interested to know what causes this change at the molecular level. The pressure increase forces the atoms closer and closer together but what triggers the change to a liquid ?

Should this be posted in the theoretical forum ?

Best regards

Bitman

 

[Aaron Barnard]

Yes, this should be posted in the theoretical forum. The critical temperature is the temperature at which the vapor pressure of a liquid equals the atmospheric pressure. This is the temperature at which the gas and liquid phases of a substance are in equilibrium. Different substances have different critical temperatures, depending on the properties of their molecules. At the molecular level, the change from gas to liquid occurs because of intermolecular forces. When the temperature decreases, the kinetic energy of the molecules decreases and the attractive forces between the molecules become more important. As these forces become stronger, the molecules move closer together, forming a liquid phase.

 

[astrokreng]

Hi Bitman,

Yes, there is a formula that can predict the critical temperature of a gas. The formula is known as the Clausius-Clapeyron equation and it is given by:

Tc = (a/R)(ln(Pc/P)) + b

Where Tc is the critical temperature, a and b are constants specific to each gas, R is the gas constant, Pc is the critical pressure, and P is the pressure at a given temperature.

The critical temperature is the temperature at which a gas cannot be liquefied by increasing the pressure alone. At this temperature, the gas molecules have enough kinetic energy to overcome the attractive forces between them, preventing them from condensing into a liquid state.

I would suggest looking for a list of gases and their critical temperatures in a physical chemistry textbook or online database. This information is readily available and can provide insight into the molecular properties of different gases and their behavior under varying conditions.

I hope this helps answer your question and provides some further information on the critical temperature of gases. If you have any more questions, please don't hesitate to ask.

Best regards,