Name: 氮 - 視頻週期表 (Nitrogen - Periodic Table of Videos)
Uploaded: 2021-01-14T10:15:46.000Z
Duration: 12 min 53 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

Nitrogen is an extraordinarily important element

We could make hundreds of youtube videos about nitrogen and still not tell you everything so

Neal and I and Brady have been in the lab we've done what we think is some quite nice

experiments just to give you a flavour of some of the things about nitrogen

So you'll see me trying to smash a banana

Going off in quite a spectacular manner and one or two other things, so it's really fun

But there is some quite a solid chemistry behind it

196 degrees centigrade is used as a coolant all over the world in laboratories and

industrially. When nitrogen comes out of the container.

It's obviously cold and you can see in the thermal

imaging how the low temperature cools everything around it. It also freezes the water vapour in the atmosphere.

So you get quite nice clouds of what looked like steam but is actually tiny particles of ice.

I used to use it. My shoes cracked through freezing in

So Grady wanted to see the professor trying to smash a banana.

fruit for example that contains water the water freezes, so the banana goes absolutely

rigid and then if you hit it with a hammer or something else the ice

shatters and it can make quite a spectacular mess.

The salt that Neal hates chemists use liquid nitrogen first of all because it's safe.

Liquid oxygen would cause or potentially could cause fires, explosions.

You've seen a liquid oxygen and cotton wool going much also easy to obtain

it's a major component of air, it's quite cheap to make. Also it has a convenient temperature of

77 degrees Kelvin (- 196 degrees centigrade), which is a useful temperature,

which freezes most things, most gases, most things that you use in the lab.

Sodium azide is a salt of sodium Na+ and the azide ion N3-

Azide comes from the French name for a nitrogen Asort.

anion, if you heat it, it can turn to nitrogen gas. N2

has a very strong bond between the two nitrogen atoms. So it releases a lot of energy

It goes to nitrogen gas and sodium vapor the sodium immediately reacts with oxygen and water vapor in the atmosphere

Sodium azide is one of the components that's used in airbags in cars

The car, if it's crashing, heats a charge of sodium azide

Which is also mixed with some other chemicals

It releases nitrogen gas very quickly and blows up the airbag.

One said advice that looks likely to be compulsory soon is the controversial airbag.

This drawing shows how it works in a crash a small detonator

releases compressed nitrogen from a tube and this inflates the bags concealed in the dash and the steering column.

But I've never seen it heated up neither Neil actually. It's really quite beautiful when you heat it up

Other resides, particularly of heavy metals like Lead, Silver, Mercury are sometimes used in

detonators to set off explosives because if you bang them they decompose very rapidly.

it can be persuaded to react with oxygen and it forms a whole series of different oxides,

compounds that contain nitrogen and oxygen and

their properties are very different. The most stable one is called nitrous oxide sometimes called

N2O has the property that it dissolves very easily.

In fact, Your brain and mine is largely fat and so N2O

dissolves well in the brain and is very good anesthetic.

It's used in childbirth, but because it dissolves well, in fact, it's also used as a propellant

Brady and I and Neil has quite a lot of fun squirting our instant cream

The cream is pressurised with N2O  probably with not a very high pressure

atmosphere a few atmospheres when you release it the

dissolved N2O bubbles out, so the liquid cream suddenly goes into a foam ready to go on your cake

(Is it still in the some of the cream when I eat the cream?)

There's probably some N2O left in the cream

but if you wanted to anaesthetise yourself by eating cream,

you would vomit long before you had enough to have any serious effect. The other two oxides of nitrogen

Nitrogen dioxide they're both quite unusual because nitrogen has seven electrons

and oxygen has six so both compounds have unpaired electrons, which gives them slightly unusual properties.

The standard way is just a heat up lead nitrate

NO3- (Pb+2NO-3)  and when you heat it up you form lead oxide

which is a sort of slightly yellowy orange color and

you make NO2, which is a brown gas and when we heated it up

we got really quite a sort of substantial plume of NO2

NO2 itself can because it has an unpaired electron can dimerise

which is a liquid at room temperature and that we have shown on one of our other videos can be used as an oxidizer

For example the lunar module taking off from the moon used N2O4 as the propellant now

It's very volatile it boils at 21 degrees C, so we have to keep it cold and we put it into the reaction chamber

There's another way of making NO2, which is the reaction of

concentrated nitric acid it's important that it's concentrated with metallic copper

and we did this in glassware so that we could collect the gas and see what happens.

So we had a vessel with the acid coming in at the top the reaction taking place and the tube at the side

going into water so we could collect the gas.

You can see that when the acid went in there were clouds brown gas

generated the NO2  before and it went down the tube and there was bubbling as it came out now

we had some quite strange effects, which we hadn't anticipated.

It's one of the exciting things about doing chemistry

demonstrations that sometimes although you understand what's going on

you see effects that surprise you when Neal added a bit more acid the NO2