A freezing liquid
Liquid nitrogen boils at -196oC, it is used as a coolant in laboratories and Industries all over the world. It is kept inside containers called Dewar flasks (named after James Dewar) which are specialised type of vacuum flask used for storing liquids whose boiling points are much lower than room temperature, when nitrogen comes out of the container, it’s obviously cold and the low temperature cools everything around it, even the water vapor in the atmosphere, so tiny particles of ice are formed and they look like a nice cloud.
Liquid nitrogen is used because of safety reasons, it’s better than the oxygen liquid which can cause fires 🔥 and explosion 💥.
Also liquid nitrogen is easy to obtain because it’s the major component of air, it’s quite cheap to make and its boiling temperature (-196oC )is a useful temperature which freezes most things.
Sodium azide NaN3 is a salt formed with sodium Na+ and the azide ion N3- which is an unstable ion, it can turn to nitrogen gas when it’s heated.
Sodium azide is used in airbags of the cars, so when it crashes, it heats sodium azide which releases nitrogen gas very quickly and blows up the airbag.
Nitrogen and oxygen
Nitrogen can react with oxygen to form different oxides with different properties
The most stable one is called nitrous oxide N2O. It dissolves very easily in fat, that’s why it is used as an anaesthetic for the brain which contains lot of fat. Also, because it dissolves well in fat it is used for instant cream.
The other two oxides of nitrogen are nitric oxide (NO) and Nitrogen dioxide (NO2). They have both unusual properties.
NO2 is a brown gas. Because it has an unpaired electron, NO2 can link to another NO2 and form N2O4 which is a liquid at room temperature and it is used as an oxidizer for rockets.
Nitric oxide (NO) is not very soluble in water, but NO reacts very easily with the oxygen in the air to make NO2.
The relevance of all these nitrogen oxides is that in the high temperatures (particularly in diesel engines) the nitrogen and the oxygen in the air can combine to make small amounts of nitric oxide (NO) and nitrogen dioxide (NO2). These nitrogen oxide are very bad, they cause air pollution, so they are the reason of many breathing problems.