Dry ice and liquid nitrogen are often used in experiments and other demonstrations. Both are extremely cold and very useful, but very different from each other. Let’s find out the differences between dry ice and liquid nitrogen, and explore more about them.
What happens when dry ice and liquid nitrogen are put together in the same container? Well, dry ice, which is denser at -110℉, sinks to the bottom, and liquid nitrogen, at -321℉, starts boiling very rapidly! Whoa! Did you imagine dry ice to be SO HOT? (sic)
Ever noticed fog machines in a party or usually in a pub? Yes, you got that right! They use dry ice in fog machines to produce smoke and spooky, foggy effects at your parties. And did you know that your favorite ice creams on earth can be frozen and kept cold by using either dry ice or liquid nitrogen?
Dry ice and liquid nitrogen are two cooling agents used pretty extensively and commercially. Dry ice is solid carbon dioxide (CO2), whereas liquid nitrogen is the liquefied form of nitrogen (N2) in the gaseous state. Their super-cold temperature is what makes them ideal for refrigerating ice creams and other food items.
Find out how in the sections below. Also, discover for yourself some differences between the two.
Dry Ice Vs. Liquid Nitrogen
As mentioned above, dry ice is the carbon dioxide gas that is solidified at about -109℉ to -110℉. Carbon dioxide takes about 0.04 percent of the Earth’s atmosphere and is found mostly in the gaseous state. However, it also exists in liquid and solid states at different temperatures and pressures. It typically looks like the snow that is hydraulically treated to form blocks and pellets. This solid state of CO2was first discovered by a French chemist, Charles Thilorier, in 1834.
Dry ice is colorless, odorless, and slightly acidic. At a temperature below -78℃ and atmospheric pressure below 5.13 atm, CO2 converts back into gaseous state, skipping the liquid state through a process called sublimation. The density of dry ice is between 1.4 – 1.6 g/cm3. Its low temperature and the ability of direct sublimation to gas makes it an ideal coolant. At room temperature, it will last for about 3 – 5 hours.
It is non-polar and has a dipole moment of zero. It has the same molecular structure as that of CO2 and is made up of two oxygen atoms that are bonded covalently with one carbon atom.
Applications in Daily Life
- The most common application of dry ice is to preserve and refrigerate food. It is used to package food items that need to be stored in cold or frozen temperatures such as ice cream and biological samples.
- Another common use of the fog machines is at nightclubs. It is also useful in theaters that require special and enchanting effects.
- It is used to freeze and remove warts. However, liquid nitrogen works better on warts as it is colder than dry ice.
- It can be used to trap mosquitoes and bedbugs because they are attracted to CO2.
- One of the important mechanical uses is blast cleaning, in order to remove the residues sitting on industrial equipment.
- It is also used in removal of dents in cars.
Precautions and Safety
- While handling dry ice, make sure you wear gloves and goggles because it being extremely cold, can cause frostbite. If touched directly, the skin can get damaged severely because of the cold temperature.
- Also remember, dry ice is not a food and is dangerous to put in individual drinks. And it goes without saying, make sure you don’t consume it directly as it may burn your throat. Many people do put it in their drinks, but if you are not sure, then don’t drink. Don’t swallow the dry ice out of the drink.
- Do not store the dry ice in your freezer. It may lead the thermostat of the freezer to shut it down.
- Make sure the room or storage area is well-ventilated.
- Do not store dry ice in a fully airtight container.
Liquid nitrogen is the nitrogen that is cooled and pressurized in its gaseous state to transform it into liquid. At standard pressure and temperature, nitrogen is a gas. The nitrogen gas comprises 78% of the Earth’s atmosphere. In comparison with dry ice, it turns into liquid when exposed to cold temperatures and pressure. It is also referred by the abbreviation, LN2, LIN, or LN. It was first liquefied in 1883 by two Polish physicists, Zygmunt Wróblewski and Karol Olszewski.
Liquid nitrogen is a colorless and non-flammable liquid having a density of 0.807 g/cm3 at its boiling point and dielectric constant of 1.43. It boils at -321℉ and freezes at -346℉. It is a cryogenic liquid that causes rapid freezing if it comes in contact with a living tissue. It can be converted into solid easily by placing it in a vacuum chamber. Its ability to maintain lower temperature even below the freezing point of water makes it an ideal choice for a refrigerant.
It is a diatomic liquid, which means that the diatomic character of N2 gas consisting of covalent bonding of two nitrogen atoms is retained even after it is liquefied.
Applications in Daily Life
- The most common use of liquid nitrogen is while making and freezing ice creams, drinks, and other food items at a lower temperature for a longer period of time.
- It is also used in cryogenic applications like cryotherapy for removal of unsightly skin abnormalities and lesions like warts by freezing and immediately removing them.
- It is great for experimenting if handled carefully.
- It is also used as a coolant for superconductors, vacuum pumps, and other equipment.
Precautions and Safety
- If handled carelessly, liquid nitrogen may result in cold burns and frostbites. Ensure that you wear cryo gloves while handling liquid nitrogen.
- It may lead to asphyxia in confined spaces if left open. Make sure you don’t inhale the extremely cold vapors.
- Do not store it in tightly sealed container, as it may result in explosion or bursting of the container due to high pressure.
- Make sure you store it in a well-ventilated area.
- Liquid nitrogen is dangerous to drink. As per the records, in 2012, a woman in England had to get her stomach removed after drinking a cocktail made with liquid nitrogen.
So, now you know that dry ice and liquid nitrogen are almost similar in uses, but made up of completely different elements. Using dry ice for making ice cream may prove time-consuming and little laborious as compared to liquid nitrogen, and liquid nitrogen may prove heavier as far as the monetary investment it concerned.
Disclaimer: This article is for educative purposes only. Please do not indulge in experiments with these cooling agents at home without professional help.