With the reaction.

You can see the orange sodium claim I technician Neil felt that we weren't really doing them scientifically enough.

We were just dropping alkaline metals into water and seeing what happened.

And we've also done the reverse experiment water falling onto sodium.

But what Neil felt is we should do something that was much more controlled.

He wanted to break ampoules glass vessels containing the alkaline metals underwater so we can watch the reaction before there is any air presence.

And also he had the second idea that we should compare the same number of atoms off the three metals that he chose.

Sodium, potassium and cesium.

But today I'm gonna show you the first experiment, which, with with sodium Neil's device, begins with a plastic box, which is filled with water with flat sides.

So you can video and you can see both under the water and what's happening on the surface inside is a device which he hasn't made the name yet, a sort of like a thumb screw.

But for test tubes, where by turning a shaft, which goes a long way away from the trough.

He can force a metal pin into the side of a test tube so that it breaks and you can film the whole thing a different speeds and from different angles.

That way, when the tube breaks, water rushes in and the reaction starts.

And the only way that the metal can become in contact with there is if it floats up to the surface in a cesium tube.

It was evacuated without any air.

In some of the other tubes, there was air you'll see in one of our videos that he wasn't quite properly sealed, so it was full of air.

But the amount of air in the tube is very small compared to the amount of hydrogen that you expect to be generated by full reaction.

The experiments were done outside so that we had bright sunlight and also so if there was an explosion, it wouldn't cause any harm in the building.

What you see is that as the pin starts breaking and the bubbles are coming out, I believe our hydrogen and the hydrogen just bubbles up to the surface.

When it gets to the surface, there is some cloudiness, which I think is probably just an optical illusion from the sun.

There may be some mist of water inside it, because from some angles they look transparent.

On the other hand, Neil and Braid, do you think it might be something more interesting, and I'm prepared to be corrected if we do more experience.

Once the reaction gets going, you get more and more bubbles.

But to begin with, there isn't much evidence of any fire.

Anything burning, the hydrogen dissipates, and then gradually the reaction goes more rapidly.

At the end, there is a huge bush, which in our first video, which about sodium effectively wipes everything out on the screen, partly because I think heat, which is generated by these reactions, is registered on video screens as just white light.

What I think happens at the end is that sodium, which has a density that is quite similar to water, is carried up by the hydrogen bubbles, and it'll reacts on the surface and with the air and explodes.

There are a number of questions that will strike you immediately.

The first thing is, it all looks very rapid, but From the point of view of a chemist, it's really pretty slow.

It took a good fraction of a second Really fast chemical reactions take place in a nanosecond, 1000 millionth of a second.

And here we're talking 10000.1 of a second, something that quite slow.

So this reaction it's fast, but it is slow enough for mechanical things like breaking of glass and so on to take place.

What, of course we haven't done is we haven't analyzed the bubbles and shown that their hydrogen.

But part of the reason for this is that the reaction of alkaline metals and water is a very well researched area.

And I've got here a PhD thesis reactions of the Liquid Alkaline Metals with Water, which was published in 1976.

This is no cutting edge research, of course.

We now have high speed cameras so that we can show you videos nice and easily.

But when these guys were researching, they had high speed.

Sydney cameras, unfortunately, lost the film, but we do have some nice photos.

So what we take with this is the a lot of this is already known.

The reason why this research was being done was because in the 19 seventies, people were building nuclear reactors with hundreds of tons of liquid sodium in them, which also had water cooling.

And people wanted to know what would happen if the sodium leaked into the water system.

So I have an 80 year old colleague, now retired, who supervised this research.

He looks a ttle our videos with some amusement and says, When will the young generation ever learn?

His point of view is that you could save a lot of results time by reading the old papers.

In fact, there is a cliche that you can save six months in the lamp with two hours in the library.

So you've seen sodium Well, you're clearly waiting like need to see potassium and cesium, but those will be in the next video.