Making SOLID Nitrogen!

Boiling point is something that we normally think of as a stable property of a substance. But it really depends on what the pressure is around the substance. So, for example, water only boils at 100 degrees Celsius if the pressure is 1 atmosphere.

So if you reduce the pressure, then those water molecules that are going quite quickly can easily escape from the water if there's no pressure pushing down on them. So you can get water to boil at room temperature. This is really boiling water. The funny thing about boiling water at room temperature is that it actually decreases the temperature of the water.

That's because all the fastest water molecules escape, leaving only the slow ones behind. We are refrigerating the water. Refrigerating the water by boiling it. Yes, yes (Laughing) That is a cool concept.

I know everyone's a big fan of liquid nitrogen, but I've never seen solid nitrogen. So we used the same trick, pumping out the very fastest nitrogen molecules. And eventually, that decreased the temperature enough that the nitrogen actually froze. (Laughing)

I'm putting a thermocouple in there so we can measure the temperature of our liquid nitrogen. And it reads... Okay, so the temperature of our liquid nitrogen is about minus 196 Celsius. Which is exactly what it should be.

And now we're going to evacuate the chamber. We're gonna suck the air out of there. You can see that the nitrogen is boiling. The temperature's dropping, minus 199, minus 200... We're coming up on the triple point of nitrogen.

I don't know. We're forming solid nitrogen. The ice is actually getting sucked up by the reduced pressure up here, and there is a higher pressure underneath the ice because the vacuum pump hasn't had a chance to work there. I've never seen solid nitrogen before.

After creating the solid nitrogen, we poured it onto a water bath. And we got the whole surface so cold that carbon dioxide actually condensed out of the atmosphere, and we formed solid carbon dioxide, dry ice, on the surface of the water. We have a solid piece of CO2.