Liquid Nitrogen
Liquid nitrogen is nitrogen that is cold enough to exist in liquid form. It is used for many cooling and cryogenic applications. Here are some liquid nitrogen facts and information about handling liquid nitrogen safely.
Liquid Nitrogen Facts
Liquid Nitrogen Facts
- Liquid nitrogen is the liquefied form of the element nitrogen that is commercially produced by fractional distillation of liquid air.
- Sometimes liquid nitrogen is denoted as LN2, LN, or LIN.
- Liquid nitrogen has the UN number 1977.
- At normal pressure, liquid nitrogen boils at 77 K (−195.8°C or −320.4°F)
- The liquid to gas expansion ratio of nitrogen is 1:694, which means liquid nitrogen boils to fill a volume with nitrogen gas very quickly.
- Nitrogen is non-toxic, odorless, and colorless. It is relatively inert. It is not flammable.
- Nitrogen gas is slightly lighter than air once it reaches room temperature. It is slightly soluble in water.
- Liquid Nitrogen Safety
- Liquid nitrogen is cold enough to cause severe frostbite upon contact with living tissue. Wear proper safety gear when handling liquid nitrogen to prevent contact or inhalation of extremely cold vapor. Make sure exposed skin surfaces are covered and preferably insulated.
- Because it boils so rapidly, the phase transition from liquid to gas can generate a lot of pressure very quickly. Do not enclose liquid nitrogen in a sealed container, as this may result in bursting or an explosion.
- Adding a lot of nitrogen to the air reduces the relative amount of oxygen. This can result in an asphyxiation risk. Cold nitrogen gas is heavier than air, so the risk is greatest near the ground. Use liquid nitrogen in a well-ventilated area.
- Liquid nitrogen containers may accumulate oxygen which is condensed from the air. As the nitrogen evaporates, there is a risk of violent oxidation of organic matter.
- Liquid Nitrogen Uses
- Freezing and transport of food products.
- Cryopreservation of biological samples.
- Coolant for superconductors, vacuum pumps, and other materials and equipment
- Cryotherapy to remove skin abnormalities.
- Shielding materials from oxygen exposure.
- Cooling materials for easier machining or fracturing.
Question: What Is the Temperature of Liquid Nitrogen? How Cold Is It? Answer: Liquid nitrogen is very cold! At normal atmospheric pressure, nitrogen is a liquid between 63 K and 77.2 K (-346°F and -320.44°F).
Over this temperature range, liquid nitrogen looks much like boiling water. Below 63 K, it freezes into solid nitrogen. Because liquid nitrogen in a usual setting is boiling, its usual temperature is 77 K.
Liquid nitrogen boils into nitrogen vapor at room temperature and pressure. The cloud of vapor that you see isn't steam or smoke. Steam is invisible vapor, while smoke is a product of combustion. The cloud is water that has condensed out of the air from exposure to the cold temperature around the nitrogen. Cold air cannot hold as much humidity as warmer air, so a cloud forms.
Liquid nitrogen is not toxic, but it does present some hazards. First, as the liquid changes phase into a gas, the concentration of nitrogen in the immediate area increases.
The concentration of other gases decreases, particularly near the floor, since cold gases are heavier than warmer gases and sink. An example of where this can present a problem is when liquid nitrogen is used to create a fog effect for a pool party. If only a small amount of liquid nitrogen is used, the temperature of the pool is unaffected and the excess nitrogen is blown away by a breeze. If a large amount of liquid nitrogen is used, the concentration of oxygen at the surface of the pool might be reduced to the point where it can cause breathing problems or hypoxia.
Another hazard of liquid nitrogen is that is the liquid expands to 174.6 times its original volume when it becomes a gas. Then, the gas expands another 3.7 times as it warms to room temperature. The total increase in volume is 645.3 times, which means vaporizing nitrogen exerts immense pressure on its surroundings. Liquid nitrogen should never be stored in a sealed container because it could burst.
Finally, because liquid nitrogen is so very cold, it presents an immediate danger to living tissue. The liquid vaporizes so quickly a small amount will bounce off skin on a cushion of nitrogen gas, but a large volume can cause frostbite.
The quick vaporization of nitrogen means all of the element boils off when you make liquid nitrogen ice cream. The liquid nitrogen makes the ice cream cold enough to turn into a solid, but it doesn't actually remain as an ingredient.
Another cool effect of the vaporization is that liquid nitrogen (and other cryogenic liquids) appear to levitate. This is due to the Leidenfrost effect, which is when a liquid boils so rapidly, it's surrounded by a cushion of gas. Liquid nitrogen splashed onto the floor appears to skitter away just over the surface. There are videos where people throw liquid nitrogen out onto a crowd. No one is harmed because the Leidenfrost effect prevents any of the super-cold liquid from touching them.
Over this temperature range, liquid nitrogen looks much like boiling water. Below 63 K, it freezes into solid nitrogen. Because liquid nitrogen in a usual setting is boiling, its usual temperature is 77 K.
Liquid nitrogen boils into nitrogen vapor at room temperature and pressure. The cloud of vapor that you see isn't steam or smoke. Steam is invisible vapor, while smoke is a product of combustion. The cloud is water that has condensed out of the air from exposure to the cold temperature around the nitrogen. Cold air cannot hold as much humidity as warmer air, so a cloud forms.
Liquid nitrogen is not toxic, but it does present some hazards. First, as the liquid changes phase into a gas, the concentration of nitrogen in the immediate area increases.
The concentration of other gases decreases, particularly near the floor, since cold gases are heavier than warmer gases and sink. An example of where this can present a problem is when liquid nitrogen is used to create a fog effect for a pool party. If only a small amount of liquid nitrogen is used, the temperature of the pool is unaffected and the excess nitrogen is blown away by a breeze. If a large amount of liquid nitrogen is used, the concentration of oxygen at the surface of the pool might be reduced to the point where it can cause breathing problems or hypoxia.
Another hazard of liquid nitrogen is that is the liquid expands to 174.6 times its original volume when it becomes a gas. Then, the gas expands another 3.7 times as it warms to room temperature. The total increase in volume is 645.3 times, which means vaporizing nitrogen exerts immense pressure on its surroundings. Liquid nitrogen should never be stored in a sealed container because it could burst.
Finally, because liquid nitrogen is so very cold, it presents an immediate danger to living tissue. The liquid vaporizes so quickly a small amount will bounce off skin on a cushion of nitrogen gas, but a large volume can cause frostbite.
The quick vaporization of nitrogen means all of the element boils off when you make liquid nitrogen ice cream. The liquid nitrogen makes the ice cream cold enough to turn into a solid, but it doesn't actually remain as an ingredient.
Another cool effect of the vaporization is that liquid nitrogen (and other cryogenic liquids) appear to levitate. This is due to the Leidenfrost effect, which is when a liquid boils so rapidly, it's surrounded by a cushion of gas. Liquid nitrogen splashed onto the floor appears to skitter away just over the surface. There are videos where people throw liquid nitrogen out onto a crowd. No one is harmed because the Leidenfrost effect prevents any of the super-cold liquid from touching them.