Andrew's Isotherms : Isotherms of CO2 at different temperatures
• At A (13.1°C) CO2 exists as gas
• On increasing pressure, at B liquefaction starts.
• At C, liquefaction is complete.
• After that, increase in pressure has little effect on volume, since liquids have low compressibility.
• Above 30.98°C, gas cannot be liquified howsoever high pressure may be applied.
• Point P (30.98°C) is the critical temperature.
