Physical properties of dry ice
Dry ice is the popular name of carbon dioxide (CO2) in its solid state. Dry ice is non-flammable, non-conductive and contains no water.
In 1835, the French chemist Charles Thilorier published the first ever description of dry ice. Upon lifting the lid of a large cylinder full of liquid carbon dioxide, he noticed that the carbon dioxide was evaporating fast and leaving a thick layer of dry ice in the cylinder. Over the next 60 years, dry ice was observed and tested by a number of scientists for the purpose of exploring all of its useful properties and potential applications.
Dry ice applications
Dry ice has multiple practical applications:
Dry ice directly converts to gas when melting and absorbs heat in the thawing process, thus reducing ambient temperature around it. This process means that dry ice can be used as a refrigerant. To induce artificial precipitation, water vapour in the air can be condensed by scattering dry ice into the upper layers of the atmosphere.
Dry ice can be utilised in dry cleaning as it removes residues, colloids and stains, e.g. oil stains.
Dry ice is also applied in medicine and cosmetics. Some dermatologists use dry ice to treat acne; this is known as cold therapy as it delicately freezes the skin. A mixture of ground dry ice and dimethyl ketone, at times blended with a little sulphur, is a frozen material used for treating acne. It is also used to remove unwanted skin formations. Liquid nitrogen and dry ice can also be used as materials for cold therapy, which can reduce inflammation.
Dry ice also finds application in the food industry. It creates an impressive visual effect when added to wine, a cocktail or a beverage. Add dry ice to ice cream as an experiment and you will find it very difficult to melt the ice cream afterwards. It can also be used as a source of carbon dioxide and to produce carbonated water and other liquids such as beer.
When dry ice is placed in water, sublimation is accelerated. This leads to the formation of thick low-lying smoke-like vapour. This is used in fog machines in theatres and nightclubs to create a mystical, dramatic effect.
Dry ice is used in large quantities in the refrigerated transport of frozen fruit, vegetables, meat and seafood at low temperature. Dry ice is also used for transporting special medication, organs, blood plasma and vaccines.
Dry ice is also an indispensable cleaning agent used for cleaning up contaminated surfaces without the use of any detergents, chemicals or organic solvents. When a contaminated surface is blasted with microscopic granules of dry ice and when they evaporate into the atmosphere, the sublimation effect is achieved, in which the contaminated layer vaporises simultaneously with the frozen granules of CO2 and ‘vanishes’ with no damage done to the surface.
Environmental aspects of dry ice
Dry ice is frozen carbon dioxide (CO2), a constituent of the earth's atmosphere. It is extracted from air and frozen. Then it evaporates, returning into the atmosphere. In other words, dry ice is not a pollutant, does not increase humidity when evaporating in a closed space, has no odour and is safe to use if you comply with the recommendations for work.
DRY ICE BLOCKS
DRY ICE PELLETS