Product Code Database
Dry ice is the solid form of carbon dioxide. It is commonly used for temporary refrigeration as CO2 does not have a liquid state at normal atmospheric pressure and sublimes directly from the solid state to the gas state. It is used primarily as a cooling agent, but is also used in at theatres for dramatic effects. Its advantages include lower temperature than that of Ice and not leaving any residue (other than incidental frost from moisture in the atmosphere). It is useful for preserving (such as ice cream) where Refrigeration is unavailable.
Dry ice sublimes at at Earth atmospheric pressure. This extreme cold makes the solid dangerous to handle without protection from frostbite injury. While generally not very toxic, the outgassing from it can cause hypercapnia (abnormally elevated carbon dioxide levels in the blood) due to a buildup in confined locations.
At pressures below 5.13 atm and temperatures below (the triple point), CO2 changes from a solid to a gas with no intervening liquid form, through a process called sublimation. The opposite process is called deposition, where CO2 changes from the gas to solid phase (dry ice). At atmospheric pressure, sublimation/deposition occurs at .
The density of dry ice increases with decreasing temperature and ranges between about below . The low temperature and direct sublimation to a gas makes dry ice an effective coolant, since it is colder than ice and leaves no residue as it changes state. Its enthalpy of sublimation is 571 kJ/kg (25.2 kJ/mol, 136.5 calorie/g).
Dry ice is non-polar, with a dipole moment of zero, so attractive intermolecular van der Waals forces operate. The composition results in low thermal and electrical conductivity.
Dry ice is typically produced in three standard forms: large blocks, small ( diameter) cylindrical pellets and tiny ( diameter) cylindrical, high surface to volume pellets that float on oil or water and do not stick to skin because of their high radii of curvature. Tiny dry ice pellets are used primarily for dry ice blasting, quick freezing, fire fighting, oil solidifying and have been found to be safe for experimentation by middle school students wearing appropriate personal protective equipment such as gloves and safety glasses. A standard block weighing approximately covered in a taped paper wrapping is most common. These are commonly used in shipping, because they sublime relatively slowly due to a low ratio of surface area to volume. Pellets are around in diameter and can be bagged easily. This form is suited to small scale use, for example at and laboratory where it is stored in a thickly insulated chest. Density of pellets is 60–70% of the density of blocks.
Dry ice is also produced as a byproduct of cryogenic air separation, an industry primarily concerned with manufacturing extremely cold liquids such as liquid nitrogen and liquid oxygen. In this process, carbon dioxide liquefies or freezes at a far higher temperature compared to that needed to liquefy nitrogen and oxygen. The carbon dioxide must be removed during the process to prevent dry ice from fouling the equipment, and once separated can be processed into commercial dry ice in a manner similar to that described above.
It is frequently used to package items that must remain cold or frozen, such as ice cream or biological samples, in the absence of availability or practicality of Refrigeration.
Dry ice is critical in the deployment of some vaccines, which require storage at ultra-cold temperatures along their supply line.
Dry ice can be used to flash freezing food or laboratory biological samples, Carbonated water beverages, make ice cream, solidify oil spills"Zapping Oil Spills with Dry Ice and Ingenuity" by Gordon Dillow Los Angeles Times South Bay section page 1 2/24/1994 and stop ice sculptures and ice walls from melting.
Dry ice can be used to arrest and prevent insect activity in closed containers of grains and grain products, as it displaces oxygen, but does not alter the taste or quality of foods. For the same reason, it can prevent or retard food oils and fats from becoming Rancidity.
When dry ice is placed in water, sublimation is accelerated, and low-sinking, dense clouds of smoke-like fog are created. This is used in , at theater, haunted house attractions, and for dramatic effects. Unlike most artificial , in which fog rises like smoke, fog from dry ice hovers near the ground. Dry ice is useful in theatre productions that require dense fog effects. The fog originates from the bulk water into which the dry ice is placed, and not from atmospheric water vapor (as is commonly assumed).
It is occasionally used to freeze and remove warts. However, liquid nitrogen performs better in this role, as it is colder, thereby requiring less time to act, and needs less pressure to store. Dry ice has fewer problems with storage, since it can be generated from compressed carbon dioxide gas as needed.
In plumbing, dry ice is used to cut off water flow to pipes to allow repairs to be made without shutting off water mains. Pressurised liquid CO2 is forced into a jacket wrapped around a pipe, which in turn causes the water inside to freeze and block the pipe. When the repairs are done, the jacket is removed and the ice plug melts, allowing the flow to resume. This technique can be used on pipes up to 4 inches or 100 mm in diameter.
Dry ice can be used as bait to trap , Bed bug, and other insects, due to their attraction to carbon dioxide.
It can be used to exterminate rodents. This is done by dropping pellets into rodent tunnels in the ground and then sealing off the entrance, thus suffocating the animals as the dry ice sublimates.
Tiny dry ice pellets can be used to fight fire by both cooling fuel and suffocating the fire by excluding oxygen."Could a Freeze Gun Put Flames on Ice" by Zantos Peabody Los Angeles Times local section B3 9/3/2002
The extreme temperature of dry ice can cause viscoelastic materials to change to Glass transition phase. Thus, it is useful for removing many types of pressure sensitive adhesives.
One of the largest mechanical uses of dry ice is blast cleaning. Dry ice pellets are shot from a nozzle with compressed air, combining the power of the speed of the pellets with the action of the sublimation. This can remove residues from industrial equipment. Examples of materials removed include ink, glue, oil, paint, mold and rubber. Dry ice blasting can replace sandblasting, steam blasting, water blasting or solvent blasting. 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. Recently, blast cleaning has been introduced as a method of removing smoke damage from structures after fires.
Dry ice is also useful for the de-gassing of flammable vapours from storage tanks the sublimation of dry ice pellets inside an emptied and vented tank causes an outrush of CO2 that carries with it the flammable vapours.
The removal and fitting of in large engines requires the use of dry ice to chill and thus shrink the liner so that it freely slides into the engine block. When the liner then warms up, it expands, and the resulting interference fit holds it tightly in place. Similar procedures may be used in fabricating mechanical assemblies with a high resultant strength, replacing the need for pins, keys or welds.
Dry ice has found its application in construction for Ground freezing, serving as an effective alternative to liquid nitrogen. This method reduces the soil temperature to approximately -70 to -74 °C, rapidly freezing the groundwater. As a result, the soil's strength and impermeability significantly increase, which is essential for the safe execution of underground construction projects.
It is also useful as a cutting fluid.
The process of cloud seeding can be done with the use of dry ice. It was widely used in experiments in the US in the 1950s and early 1960s before it was replaced by silver iodide. Dry ice has the advantage of being relatively cheap and completely non-toxic. Its main drawback is the need to be delivered directly into the supercooled region of clouds being seeded.
The dry ice bomb device was featured on MythBusters, episode 57 Mentos and Soda, which first aired on August 9, 2006. It was also featured in an episode of Time Warp, as well as in an episode of Archer.
In 2012, the European Space Agency's Venus Express probe detected a cold layer in the atmosphere of Venus where temperatures are close to the triple point of carbon dioxide hence it is possible that flakes of dry ice precipitate. "A curious cold layer in the atmosphere of Venus". . European Space Agency (1 October 2012).
Observations from the Uranus flyby by Voyager 2 indicates that dry ice is present on the surface of its large moons Ariel, Umbriel and Titania. Scientists speculate that the magnetic field of Uranus contributes to the generation of CO2 ice on the surfaces of its moons. Voyager 2 observations of Neptune's moon Triton suggested the presence of dry ice on the surface, though followup observations indicate that the carbon ices on the surface are carbon monoxide but that the moon's crust is composed of a significant quantity of dry ice.
Dry ice is assigned a UN number, a code for hazardous substances: UN 1845. Dry ice is not classified as a dangerous substance by the CLP Regulation, or as a hazardous material by the United States Department of Transportation for ground transportation. However, in the US, it is regulated as a dangerous good when shipped by air or water. International Air Transport Association (IATA) regulations require specific diamond-shaped black-and white labelling to be placed on the package. The package must have adequate ventilation so that it will not rupture from pressure in the event that the Dry Ice begins to sublime in the packaging. The Federal Aviation Administration in the US allows airline passengers to carry up to per person either as checked baggage or carry-on baggage, when used to refrigerate perishables.
At least one person has been killed by carbon dioxide gas subliming off dry ice in coolers placed in a car. In 2020, three people were killed at a party in Moscow after 25 kg of dry ice was dumped in a pool; carbon dioxide is heavier than air, and so can linger near the ground, just above water level.
Industrial
Dry ice can be used for loosening asphalt floor tiles or car sound deadening material, making them easy to prise off, as well as freezing water in valveless pipes to enable repair.
Scientific
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. Dry ice and acetone forms a cold bath of , which can be used for instance to prevent thermal runaway in a Swern oxidation.
Dry ice bombs
A "dry ice bomb" is a balloon-like device using dry ice in a sealed container such as a plastic bottle. Water is usually added to accelerate the sublimation of the dry ice. As the dry ice sublimes, pressure increases, causing the bottle to burst with a loud noise. The screw cap can be replaced with a rubber stopper to make a water rocket.
Extraterrestrial occurrence
Following the Mars flyby of the Mariner 4 spacecraft in 1966, scientists concluded that Mars' polar caps consist entirely of dry ice. However, findings made in 2003 by researchers at the California Institute of Technology have shown that Mars' polar caps are almost completely made of water ice, and that dry ice only forms a thin surface layer that thickens and thins seasonally. A phenomenon named dry ice storms was proposed to occur over the polar regions of Mars. They are comparable to Earth's thunderstorms, with crystalline CO2 taking the place of water in the clouds. Dry ice is also proposed as a mechanism for the geysers on Mars.
Safety
Prolonged exposure to dry ice can cause severe skin damage through frostbite, and the fog produced may also hinder attempts to withdraw from contact in a safe manner. Because it sublimes into large quantities of carbon dioxide gas, which could pose a danger of hypercapnia, dry ice should only be exposed to open air in a well-ventilated environment. For this reason, in the context of laboratory safety dry ice is assigned label precaution Industrial dry ice may contain contaminants that make it unsafe for direct contact with food. Tiny dry ice pellets used in dry ice blast cleaning do not contain oily residues.
Drink
Dry ice is sometimes used to give a fog effect to . One bar patron who accidentally ingested pellets from a drink suffered severe burns to his esophagus, stomach, and duodenum, causing permanent problems with eating. Rapid sublimation could cause gas buildup that ruptures digestive organs or suffocation. Products that contain dry ice and prevent it from being accidentally ingested eliminate these risks while producing the desired fog effect.
Footnotes
General bibliography
(2025). 9780781775137, Lippincott Williams & Wilkins. ISBN 9780781775137
External links
|
|
