The main difference between gaseous carbon dioxide (CO2) and liquid carbon dioxide lies in their physical states at different temperatures and pressures.
Physical State: Gaseous carbon dioxide is the form of CO2 that exists at normal temperature and pressure conditions (approximately 1 atmosphere and temperatures above -78.5 degrees Celsius). It is a colorless, odorless gas. On the other hand, liquid carbon dioxide is the state of CO2 when it is cooled and pressurized below its critical point (approximately 31 degrees Celsius and 73.8 atmospheres). In the liquid state, carbon dioxide appears as a clear, colorless liquid.
Density: Liquid carbon dioxide is much denser than gaseous carbon dioxide. At room temperature and atmospheric pressure, the density of gaseous CO2 is about 1.98 kg/m³. However, when carbon dioxide is compressed and liquefied, its density increases significantly, reaching approximately 770 kg/m³.
Storage and Transport: Gaseous carbon dioxide is typically stored and transported in pressurized cylinders or tanks. These containers need to withstand high pressure to keep the gas compressed. Liquid carbon dioxide, on the other hand, is stored and transported in specially designed tanks or cylinders that can withstand both pressure and low temperatures. Since liquid CO2 has a much higher density, it requires smaller storage volumes compared to gaseous CO2.
Applications: Gaseous carbon dioxide is commonly used in various applications such as carbonation of beverages, refrigeration systems, and as a shielding gas in welding. Liquid carbon dioxide finds applications in dry ice production, fire extinguishers, extraction processes, and as a cooling agent in certain industries.
It's important to note that the transition from gaseous to liquid carbon dioxide and vice versa depends on changes in temperature and pressure. By manipulating these factors, carbon dioxide can be converted from one state to another, allowing it to be utilized in different ways depending on the intended application.