N2-siastic Liquids

By Saksham Bambha

A relatively large portion of the Earth’s atmosphere is oxygen, which is required for the survival of almost all living organisms. Taking up about 21% of the air we breathe, oxygen’s presence is only dwarfed by one other gas – nitrogen.

That’s right, there’s nearly four times as much nitrogen in the air than there is oxygen. It may seem rather boring as a colourless, odourless and tasteless gas, but the fun begins at -196°C, which is nearly twice as cold as the lowest natural temperature ever recorded on Earth!

liquid-nitrogen-and-dewar
When  liquid nitrogen is poured out of its cryogenic dewar, it gives off a light mist that feels cool to the touch.

My curiosity for nitrogen was born when I attended Mr Subhash’s nitrogen show at Snow City. The three experiments of his that piqued my interest compelled me to research the science behind them.

Shards of Flowers

The first experiment demonstrated the extreme cryogenic property of liquid nitrogen. You’ve all felt the softness and flexibility of those small, bunches of flowers along the footpaths, right? Upon dipping and removing the flowers from the liquid, however, they crumbled in his hands like thin sheets of glass.

What made them so fragile all of a sudden? Well, flowers contain a lot of water, which instantly freezes upon touching liquid N2. Ice crystals would hence form within the flowers, making them very brittle. Matter expands when it gains heat, so touching them would make them shatter.

Pressure and Bangs 

His second experiment showed us just how powerful pressure can be. He poured liquid N2 into a container and capped it to seal it. With a sudden loud bang, the cover flew across the room! How had this cold liquid caused such an explosive reaction all by itself?

Well, nitrogen takes up a lot more space as a gas than as a liquid as the liquid-to-gas expansion ratio is 1:694. Release is the only answer to subside the built up pressure from the gas, which is the cap comes off, thus producing the loud bang.

Vanishing in a Mist

The third, most exciting experiment of the morning showed how clouds are made! Mr Subhash quickly dumped boiling water into a tub of liquid N2 on the ground. All of a sudden, he disappeared behind a massive cloud of mist!

The temperatures of liquid N2 and boiling water differ by almost 300°C, so when the two come into contact, heat is quickly transferred from the hot water to the cold liquid. This produces nitrogen vapour, which still has a very low temperature. Hence, water vapour in the surrounding air condenses quickly, forming water droplets that we see as mist.

All the experiments showed me that materializing a few basic scientific concepts can really drop jaws. The fact that most of our modern day scientific knowledge is based around the simplest workings of nature amazes me.

If you would like to watch liquid nitrogen in action with your own eyes, come on down to Snow City and enjoy a sunny afternoon in our sub-zero degree snow chambers!

explore-the-arctic

While you’re there, be sure to check out the Explore the Arctic exhibition! It explains what it really takes to live in the Arctic, how people have done it in the past, and how animals have evolved to withstand the harsh, unfavourable conditions.

Click here for more information on Snow City events and activities.

See you there!

Saksham Bambha is a student at Raffles Institution, who was interning at Science Centre for two weeks in August 2016.

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