Please explain: The liquefaction behavior of temporary gases like CO2 approaches that of N2, O2 (permanent gases) as we go above critical temperature.
Abhishek Dogra , 6 Years ago
Grade 11
1 Answers
Arun
Last Activity: 6 Years ago
The liquefaction of a gas occurs when the intermolecular forces of attraction reach a point (or become that much high) that they become capable to bind the gas molecules together to convert it into a liquid state. The critical temperature of the gas on the other hand, is the measure to identify the strength of the intermolecular forces of attraction.
As we move above the critical temperature, the liquefaction behaviour of CO2 would approach that of N2 and O2due to the same reason. When liquefaction is complete, a steep curve is observed, and when we increase the temperature, the horizontal portion start becoming smaller, and after reaching a temperature 30.98oC, it gets reduced to a point 'E'. Above this temperature, we cannot liquefy the gas but we can apply high pressure. So, this temperature of 30.98oC is known as critical temperature.
So, weaker the intermolecular forces of attraction, the more difficult it would be to liquefy the gas, and therefore, the critical temperature will be lower for that gas. Carbon dioxide gas has strong intermolecular forces of attraction, so they can be easily liquefied and hence, there critical temperature would be higher. And, CO2 below the critical temperature is known as carbon dioxide vapour. Next, in N2 and O2 , intermolecular forces of attraction are weak, therefore it would be difficult to liquefy these gases, and thus their critical temperature would be lower than these gases.