| Carbon dioxide is an inorganic gaseous carbon | | | | process to encourage the formation of a liquid. If |
| compound. As early as the 1600s, people had | | | | the gas inside the vessel is roughly at room |
| started to think about this gas, although they | | | | temperature, liquefaction starts when the |
| didn't know what it really was and what to call it. | | | | pressure is about 870 pounds per square inch |
| Flemish chemist Jan Baptist van Helmont made | | | | (ppsi), or about 6,000 kilopascals. |
| observations which hinted about the existence of | | | | The next step is pretty simple. In any given |
| carbon dioxide, setting the stage for breakthrough | | | | chunk of matter, there will be certain molecules |
| work in the 18th century by Joseph Black, a | | | | moving very fast, and some moving much more |
| Scottish chemist who identified carbon dioxide and | | | | slowly. Their average velocity is what we call the |
| explored many of its properties. By the 1800s, | | | | temperature. After enough heat evaporates, the |
| scientists had succeeded in creating and studying | | | | temperature of the liquid drops below freezing, a |
| other forms of carbon dioxide, such as its solid | | | | phase transition occurs, and we are left with solid |
| form. | | | | carbon dioxide – dry ice. Dry ice is usually |
| At room temperature, carbon dioxide takes the | | | | stored in insulated containers. When exposed to |
| form of an odorless, colorless gas which is | | | | air, it starts to give off carbon dioxide gas |
| incombustible in normal conditions. Carbon dioxide | | | | immediately, because the temperature difference |
| can be forced into a solid form, in which case it is | | | | between the dry ice and the environment is |
| known as dry ice, and the gas is toxic to animals | | | | sufficiently large that it mostly skips the liquid |
| in high concentrations. People who happen to inhale | | | | phase and just turns into gas. Some carbon |
| too much carbon dioxide essentially suffocate, | | | | dioxide is turned into vapor. Dry ice is used all the |
| ultimately falling into unconsciousness as their | | | | time to produce artificial fog for stage |
| oxygen saturation level drops. | | | | performances. It can also be used in combination |
| The gas has a wide range of commercial uses, | | | | with light shows, scattering the light so that it can |
| from the production of lasers to the carbonation | | | | be easily seen. It has become increasingly |
| of soft drinks. This compound exists naturally in | | | | popular in respect of its uses in the past few |
| the Earth's environment, and is produced in a | | | | years. The most common use of dry ice is in |
| variety of ways. Commercial carbon dioxide is | | | | the food industry, where it's used to preserve |
| usually derived from the byproducts of industrial | | | | perishable items and to carbonate liquids. Adding |
| processes. In addition to its production through | | | | dry ice to any fruit juices or water will result in a |
| respiration and combustion, the compound is | | | | sparkling drink. Dry ice also prevents the growth |
| produced through decomposition of organic | | | | of bacteria, so it can be used to preserve dry |
| materials as well. This gas is used for things like | | | | seeds, grains. |
| creating an inert environment for fire suppression, | | | | A simple use of dry ice is to freeze fruits. Fruits |
| and the carbonation of beverages, among many | | | | frozen with dry ice will thaw firm, not soggy. Pop |
| other things. | | | | Rocks, a carbonated candy that "explodes" when |
| Amounts of carbon dioxide in the environment | | | | put in the mouth, is made with pressurized dry |
| prior to the advent of the 20th century were | | | | ice. Campers have another use for dry ice: they |
| kept stable by plants, which were capable of | | | | can keep food fresh for a longer period of time |
| absorbing carbon dioxide. While this gas is entirely | | | | without having to worry about sogginess. |
| natural, some people realized about rising carbon | | | | Another use for dry ice has to do with medicine, |
| dioxide levels towards the end of the 20th | | | | where it's commonly used to preserve and ship |
| century and became concerned having found that | | | | biological samples. Cosmetic surgeons use dry ice |
| humans were producing too much carbon dioxide | | | | to freeze warts for easy removal. The |
| for plants to process, a practice which could | | | | entertainment industry also has a popular use for |
| potentially lead to serious environmental problems. | | | | dry ice. When dry ice comes in contact with |
| Now this humble gas has become a topic of | | | | water, it condenses and forms a thick white fog. |
| interest for humans because it is classified among | | | | Because dry ice can shrink metal, a common use |
| the offensive gases, gases which impact the | | | | of dry ice is to pop out small dents and to shrink |
| Earth's environment when they reach high | | | | machine parts before assembly. |
| concentrations in the atmosphere. | | | | A lesser known use for dry ice has to do with |
| Dry ice is very useful as a coolant because of its | | | | keeping mosquitoes and some other insects |
| low temperature, -109.3°F (-78.5°C). It is also | | | | away. Mosquitoes are attracted to CO2 and |
| relatively easy to make. Scientists sometimes | | | | naturally flow towards dry ice. We can place |
| need just a small quantity of dry ice which can be | | | | some pieces of dry ice around a mosquito trap to |
| achieved easily. A mixture of gaseous carbon | | | | keep mosquitoes away. Wood beetles can be |
| dioxide and dry ice is produced when part of the | | | | eliminated from furniture by placing the piece |
| escaping gas condenses on the cloth. This | | | | inside a sealed freezer with several pounds of dry |
| approach is the most straightforward way to | | | | ice. The insects and eggs will suffocate within 24 |
| produce a small amount of dry ice for laboratory | | | | hours. However, dry ice can be dangerous if not |
| use. | | | | handled properly as with a temperature of |
| To produce larger quantities of dry ice, | | | | -109.3°F (-78.5°C), it can severely burn the skin |
| evaporative cooling is necessary. First, liquefied | | | | and cause suffocation if inhaled. The use of special |
| carbon dioxide is produced by compressing carbon | | | | gloves is highly recommended when handling dry |
| dioxide gas. Because the temperature of a | | | | ice. If working with dry ice indoors one must |
| substance increases as it is compressed, the gas | | | | ensure that the space is well ventilated. |
| must be cooled throughout the compression | | | | |