We're gonna put some sodium into liquid ammonia.

So what happens is that the sodium, ah, reacts,

it releases an electron, becomes sodium single plus,

and those electrons get solvated by the ammonia.

And it's a really unusual thing in chemistry,

to have just electrons themselves being solvated.

Here we have a Dewar, this is just like you would put...

a Thermos flask or something, you would put your

cold drink or hot tea in.

And in it we've got some solid CO2, cardice,

and acetone. So that brings the whole temperature

down to about -78C, and we need to do that

because ammonia boils at -33C. So we've got

ammonia in this cylinder over here.

We've just condensed some of that into this

sealed tube, which, currently, is not sealed,

but we're using this because it's got nice thick glass.

So as we put the sodium in,

you'll see that blue colour forming.

It'll obviously heat up because there's some solvation

going on, some heat of solvation, so we'll have to

dunk it back into the cold bath

just to stop all the ammonia from boiling off.

So we've got to cut some sodium up.

We have a big lump of sodium, cut some bits off that.

And we're gonna put smaller chunks in.

This is gonna go in there, and hopefully it will not

be too vigorous a reaction, there you go. So you can see

that blue colour already forming as the sodium reacts

with the, ah, liquid ammonia.

So it's gone a nice, deep blue colour.

I'll just dip that back in to keep it cold.

[Brady] Wow! It's like ink.

[Dr. Stockman] Yeah, yeah.

So the sodium wants to lose an electron,

wants to be sodium plus.

It's much happier being sodium plus.

So it's releasing those electrons into the ammonia

solution. They're being solvated, which is why you get

this intense blue colour.

It's that solvation complex.

So if we get the concentration of electrons high enough,

then it changes colour again, it goes to a sort of

metallic colour, so we need to add in a reasonable

amount of sodium to get that to happen.

And what will happen is that the ammonia with all the

electrons in, that's slightly more dense,

and so that separates out from just ammonia

and you'll get two layers.

You'll get a sort of metallic-y bronze

sort of coloured layer.

Put some more sodium in there.

And you can hear it fizzing as it reacts.

So we've got a really, really intense blue colour now.

Almost looks black. So let's put that in there.

I would have thought that would be enough,

but you never know.

See, we're already starting to see some of that bronze

on the surface.

OK, so we've added some more sodium,

gone from very deep blue to almost black.

We're starting to see some signs of this metallic sheen.

But we don't really want to put too much of that on,

because otherwise we'll boil it all off.

So we're trying to get the molarity

of the electrons in the solution to a certain point where

we get a separation of the layers.

We get the solvated electrons will look sort of metallic-y,

and the rest of it will look...

Well, we'll see what it looks like.

[Brady] Oh yeah, now we're seeing it.

Yeah, yeah.

Well, we're reacting the sodium with the isopropanol,

so now we're making sodium isopropoxide.

So, all the electrons will be reacting away,

again we'll get hydrogen gas in there.

Bit more...

So we're getting this sort of gray sodium isopropoxide...

[Brady] It's an ugly old thing, that.

[Dr. Stockman] ...solution. Yeah, looks like an

experiment gone wrong at the moment.

It's not; it's doing what it should do,

it's making everything safe so that we can dispose of it.

The last remnants of this metallic solution here.

[Brady] Oh yeah, it looks metallic still!

[Dr. Stockman] Looks... yep.

There's a lot of electrons in there.

We put quite a lot of sodium in there.

[Brady] These electrons that are in there, like,

they're free, are they? They're just like roaming...

[Dr. Stockman] They're solvated, so the ammonia...

There are many amonias around the electrons...

and at a certain concentration,

the electrons reflect the light

and you can see it as this sort of metallic solution.

The electrons are getting less concentrated

in this bit down here,

and more concentrated up here where they're reacting.

We can see some nice flow going on.

Gonna put that down before it goes away with my gloves.

[Brady] Oh yeah. Yeah it's... it's flowing up!

[Dr. Stockman] Yeah!

Liquid metal.

Unlike mercury, it's not silvery coloured,

it's gold coloured, or bronze coloured.

[Brady] So what's the blue and the gold...coppery...

What's happening there?

[Dr. Stockman] It's different concentrations of electrons

in solution, that's the only difference.

[Brady] Look at that, that's the separation we were looking for.

[Dr. Stockman] That's right.

So the gold-coloured bit has more electrons,

and the blue, less.

And you can see on the bottom it's just going clear

where the isopropanol's reacted.

[Brady] Huh. Isn't that funny.

Quenching of it, actually, is more interesting than the, uh...

[Dr. Stockman] Yeah, yeah. Often the case!

[Brady] What's going on at the top there

with that crusty sort of powdery-ness?

[Dr. Stockman] This white stuff up here could be

let's see, the sodium amide,

or sodium isopropoxide, which is sort of a white solid.

So that is really quite pretty there. I'll squirt it

[Brady] Yeah, thanks. [Dr. Stockman] ...to make it clear again.

[Brady] Yeah that's the way.

[Dr. Stockman] Look at that, that is very pretty!

[CGP Grey] ...have a real chance of spreading to other people

and to their conversations, and that's just no good.

And that would make me feel very guilty.

[Brady] So these months that you famously spend

researching videos... [Grey] Yes.

[Brady] Are you wanting them to be really correct

because you feel this responsibility

to make the world a better place, or because you fear

hateful comments and criticism, which is it?

[CGP Gray] (Laughs) Um...

I... I would say...