Properties of liquid nitrogen. Laboratory experiments with liquid nitrogen
Application and safety rules
It is one of the aggregate states of nitrogen. Special properties of the substance are:
- has no color or taste;
- comparative inertness (at high temperatures bonds with lithium, magnesium, oxygen, hydrogen);
- does not cause corrosion;
- not flammable;
- not poisonous;
- boiling point = -196 °С.
Application of liquid nitrogen (LN):
In industry — for cooling systems, creating high pressure in plastic bottles when bottling oils and non-carbonated beverages, and obtaining ammonia.
In cosmetics — cryotherapy (massage, removing papilloma).
In medicine — for conducting surgical operations.
In cooking — for preparing ice cream and sorbet.
Necessary safety measures in working with LN
The liquid must be stored in special dewars.
Don’t seal the neck of the container tightly – you can risk damaging the container and causing an explosion.
Keep track of the nitrogen level in the cylinder – with a small residue of liquid, impurities condense.
When refilling or removing material, don’t look into the container – this can damage the mucous membranes.
Protect exposed areas of skin from cryogen vapor (long shirt sleeves, mask, glasses).
Laboratory work with liquid nitrogen
Experiment №1“Ice flower”
The most popular experiment. You’ll need a dewar containing liquid nitrogen and a rose (or any other flower, as long as it has a long stem).
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Immerse the flower in the container for 15-20 seconds. As a result you’ll get a crystal-like rose, which will break from a strong blow. This method is used by cooks nowadays to prepare salads.
Experiment №2 “Liquid air”
Transparent balloon and LN.
- inflate the balloon.
- immerse it in LN.
Result: the impact of liquid nitrogen, the air balloon reduces in volume, and the air condenses into liquid.
Experiment №3 “Big balloon”
If you fill a balloon with 1 liter of LN, you can observe the balloon expand by 70 times. However, you must be careful, as under the impact of liquid nitrogen the walls of the balloon become very fragile, which can cause an explosion. For a more spectacular experiment you can use a plastic bottle filled with LN, and place it in a barrel of water.
Experiment “Ice cream”
- 1 glass of lukewarm milk;
- 50 gr. of cream;
- 3 egg yolks;
- 100 gr. of sugar.
- beat the egg yolks with sugar;
- add milk and cream to the mixture;
- thoroughly mix, and pour in liquid nitrogen.
The ice cream can be eaten immediately.
Experiment №5 “Fog”
If you add liquid nitrogen to boiling water, intense boiling will take place, creating the effect of white fog.