Can carbon dioxde be liquified?
Carbon dioxide has no liquid state at pressures below 5.1 atm, but is a solid at temperatures below -78 °C. In its solid state, carbon dioxide is commonly called dry ice. Carbon Dioxide is an acid gas, this can be proved by putting litmus paper into it – the litmus changes its color from blue to pink. Liquid and solid carbon dioxide are important refrigerants, especially in the food industry, where they are employed during the transportation and storage of ice cream and other frozen foods. Solid carbon dioxide is called “dry ice” and is used for small shipments where refrigeration equipment is not practical. Liquid carbon dioxide (industry nomenclature R744 / R-744) was used as a refrigerant prior to the discovery of R-12 and is likely to enjoy a renaissance due to environmental concerns. Its physical properties are highly favorable for cooling, refrigeration, and heating purposes, having a high volumetric cooling capacity. Due to its operation at pressures of up to 130 bars, CO2 syste
