Gaseous Carbon Dioxide (CO2) has a slightly irritating smell, is colorless and heavier than air. It freezes at -78.5C and forms dry ice. It is soluble in water. But produces CO2 by burning excess air with hydrocarbon fuel. Characteristics Colorless liquefied high-pressure gas slightly acidic. Grade Technical Grade: 99.5% Min, Food and Medical: 99.54% Min. Typical Applications: Metal Welding hardening, Firefighting Carbonation of soft drinks, PH control in water treatment .