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Asked by ladysovereignezza to David, Luna, Mark, Melanie, Probash on 21 Mar 2011 in Categories: General.
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David Pyle answered on 20 Mar 2011:
Because it makes things very cold (-196 C). Our idea of ‘usual’ is based on our experience of standard conditions, 1 atmosphere pressure and about 15 – 25 C. Many materials have physical properties that change with temperature, and liquid nitrogen can be used to show this.
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Melanie Stefan answered on 21 Mar 2011:
Because it makes things become colder than usual. Nitrogen is liquid at less than -196 Celsius, which is far colder than anything we experience in our day-to-day lives.
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Luna Munoz answered on 21 Mar 2011:
I know that liquid nitrogen is very cold and so would freeze anything quite easily. There are some horror movies that use liquid nitrogen in very effective, though not so believable, ways.
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Probash Chowdhury answered on 21 Mar 2011:
When a liquid or gas is in it’s normal state at room temperature the molecules have a certain amount of energy which allows them to move about and a lot of space between molecules (gases more than liquids). The temperature of liquid nitrogen is about -200 deg Celsius (compared to roughly 25 deg Celcius at room temperature). This extreme cold removes all that energy from the liquids and gases and the molecules stop moving and shrink together. Solids in their normal state at room temperature have all their molecules packed close together with very little movement of the molecules (or elasticity in the case of rubbers). This is what the molecules in liquids and gases are exposed to liquid nitrogen.
By the way, solids become brittle in liquid nitrogen because the little energy that the molecules have is taken away and the bonds between the molecules become stiff but not strong – and elasticity reduces or disappears. This results in brittleness.
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