Dry ice

It is colourless, odourless, non-flammable, and slightly acidic. CO2 changes from a solid to a gas at −78.5 °C (−109.3 °F) with no intervening liquid form, through a process called sublimation. A dry ice bomb is a bomb-like device constructed out of a dry ice and water-filled container, such as a plastic bottle.

This can remove residues from industrial equipment. The approximate volume of carbon dioxide gas produced by melting a known mass of dry ice can be calculated using the Ideal gas law. The bomb was featured on MythBusters - episode 57 Mentos and Soda, which first aired on August 9, 2006. Prolonged exposure to dry ice can cause severe skin damage through cold burns, and the fog produced may also hinder attempts to withdraw from contact in a safe manner.

The primary environmental residue of dry ice blasting is the sublimed CO2, thus making it a useful technique where residues from other blasting techniques are undesirable. In laboratories, a slurry of dry ice in an organic solvent is a useful freezing mixture for cold chemical reactions and for condensing solvents in rotary evaporators. The process of altering cloud precipitation can be done with the use of dry ice. Dry ice functions as an ingredient in dry ice bombs. This technique can be used on pipes up to 100 millimetres (3.9 in) in diameter. Dry ice can be used as bait to trap mosquitoes and other insects, due to their attraction to carbon dioxide. An alternative method to cooling computer parts is with the use of dry ice.

Dry ice, sometimes referred to as Cardice or as card ice is the solid form of carbon dioxide. Dry ice pellets are shot out of a nozzle with compressed air.

Pellets are around 1 cm (0.4 in) in diameter and can be bagged easily. Dry ice blasting can replace sandblasting, steam blasting, water blasting or solvent blasting.

This purpose is overshadowed by more conventional ways with fans, heat transfer fluids, liquid nitrogen, or phase change cooling. Dry ice can be used to loosen asphalt floor tiles making them easy to pry up. One of the largest mechanical uses of dry ice is blast cleaning. A standard block weighing approximately 30 kg is most common.

Unlike most artificial fog machines, in which fog rises like smoke, fog from dry ice hovers above the ground. It is occasionally used to freeze and remove warts. Plumbers use equipment that forces pressurised liquid CO2 into a jacket around a pipe; the dry ice formed causes the water to freeze, forming an ice plug, allowing them to do repairs without turning off the water mains. This is used in fog machines, at theaters, discothèques, haunted houses, and nightclubs for dramatic effects.

As the dry ice sublimates, pressure builds up, causing the bottle to explode. The opposite process is called deposition, where dry ice changes from the gas to solid phase. The density of dry ice varies, but usually ranges between about 1.4 and 1.6 g/cm3 (87–100 lb/ft3). Dry ice is non-polar, with a dipole moment of zero, so attractive intermolecular van der Waals forces operate. It is generally accepted that dry ice was first observed in 1834 by French chemist Charles Thilorier, who published the first account of the substance. The alternative name Cardice is a registered trademark of Air Liquide UK Ltd. Dry ice is easily manufactured. Dry ice is typically produced in two standard forms: blocks and cylindrical pellets.

Because it sublimates into large quantities of carbon dioxide gas, which could displace oxygen-containing air and pose a danger of asphyxiation, dry ice should only be exposed to open air in a well-ventilated environment. Although dry ice is not classified as a dangerous substance by the European Union, Scientists following the Mariner 4 spacecraft in 1966 concluded that Mars poles were made entirely of dry ice. . This form is suited to small scale use, for example at grocery stores and laboratories. The most common use of dry ice is to preserve food, using non-cyclic refrigeration. It is frequently used to package items that need to remain cold or frozen, such as ice cream or biological samples, Moreover, dry ice can be used to flash freeze food, When dry ice is placed in water sublimation is accelerated, and low-sinking dense clouds of fog (smoke-like) are created.

These are commonly used in shipping, because they sublimate slowly due to a relatively small surface area. Examples of materials being removed include ink, glue, oil, paint, mold and rubber.

It is commonly used as a versatile cooling agent. Dry ice is the solid form of carbon dioxide (chemical formula: CO2), comprising two oxygen atoms bonded to a single carbon atom.