Phase diagram of carbon dioxide template

Schematic P–T phase diagram of CO₂: dry ice, liquid, gas, positive solid–liquid slope, triple point −56.6 °C / 5.11 atm, critical point 31.0 °C / 72.8 atm, sublimation at −78.5 °C.

What the template shows

• The triple point lies above 1 atm, so solid CO₂ sublimes instead of melting
• sublimes at 1 atm
• Solid (dry ice)
• Triple point
• Critical point
• schematic, not to scale
• Triple point at −56.6 °C and 5.11 atm: liquid CO₂ only exists above 5.11 atm, so at 1 atm dry ice sublimes at −78.5 °C.
• The solid–liquid line slopes to the right (positive), as for most substances: the solid is denser than the liquid.
• Critical point 31.0 °C, 72.8 atm: supercritical CO₂ is a mild, easily removed solvent (decaffeinating coffee, extraction).
• CO₂ fire extinguishers hold the liquid under its own vapour pressure, about 57 bar at 20 °C.
• Every part of this figure is editable · sources on the template card

Drawn with 171 shapes – every one editable in MolDraw.

Sources

• Atkins, de Paula & Keeler, Atkins' Physical Chemistry, 11th ed., OUP 2018, ch. 4 Textbook
• NIST Chemistry WebBook: carbon dioxide Database