So in this video we're going to do some demonstrations with liquid nitrogen.
Now nitrogen is quite common. In fact, 70 percent of the air that you breathe is nitrogen. But it's
a gas in the air. But if I get it cold enough and that's minus 200 degrees, it becomes a liquid.
So when I pour it into this beaker, it's boiling, it's going from liquid to gas.
But the fog you see around it is actually water vapour in the air condensing so we get the fog
and if I put it on the table you can get some more. Now i'm going to pour this into a bowl.
Won't last long, probably only last a few minutes before it all boils away.
Now this is pretty weird. I have some graham crackers and I'm gonna put them in there
so they're gonna get really cold. I can put my finger in there
as long as i do it fast. I can't hold my finger in there, otherwise it would freeze.
So i have the crackers in there - they're going to also get down to minus 200 degrees.
I don't know if you can hear it. I can hear it. It's still boiling. Just give it a little
time and then i'm going to do something that you would think would be kind of foolish.
I'm going to take one of these crackers out.
Let me see if you can guess what i'm going to do with it. All right, gotta be quick.
So now let's see what else we can do with liquid nitrogen.
Okay, what i'm going to do now is I'm going to pour some liquid nitrogen into this water bottle.
And what's going to happen is it's boiling in there so it's changing to nitrogen gas,
but of course it's able to escape. Now I'm going to seal it so now the gas can't escape and what's
going to happen is the gas pressure inside this bottle is going to get very ,very large. Enough
to burst the bottle. So let's see how much power that has. So i'm going to seal it.
Now let's see what happens.
Okay that one did not go quite as expected. I probably should just left it longer. What I've
done now is I put some water in there so now it should go much much quicker and i'm also going to
use a much stronger bottle and a bigger bottle because we want a bigger explosion than that.
That was pretty good. Now let's go bigger. So this bottle is also strong but a lot bigger.
So I'm going to seal it. Trap the gas in there.
And get out of here.
I think that might be big enough, so anyway that's what you can do with liquid nitrogen.
Now for the finale. Let's put a bottle
in this cannon. So Dennis is putting liquid nitrogen in the bottle.
And let's see what it can do to these ping-pong balls.
I don't think it's going to work. Uh John, I hear it hissing and when it hisses that
means the lid's not on there. So Dennis, could you get a couple more bottles from the physics
room and we'll do this all again? It'll just take a few minutes and if you can't find it...