So Potassium metal is very reactive.
One of my colleagues who used to work with it,
described it as evil.
So we've come out behind the chemistry department.
In the open air. To try and do
a re-take of the Potassium video.
The last sample of Potassium was very very small,
maybe 500mg.
It will react, it is so reactive that if you have it
in a box with Argon, so that it can't get Oxygen
from anywhere, it will take the Oxygen out of paper.
Which is, paper is a compound of Carbon, Hydrogen and Oxygen.
And it can extract this.
It's a reactive element. It's used in our body all the time.
We have like, lots of Potassium floating around.
And we've got some samples here, about a gram,
maybe a gram and a half of each. It's a pretty big
chunk of Potassium this.
Ready? Yeah.
Very satisfying reaction.
After completing the 100 meters dash...
Like Sodium it'ss quite a low melting point metal.
And if you mix Sodium and Potassium together,
to make so called Sodium Potassium amalgam,
it's called NaK, by those who work in the trade,
Na for Sodium, K for Potassium. NaK is a liquid at room temperature.
It looks a bit like Mercury. A silver liquid.
It's very light. And I never played with it,
but people say that if you try and drop it on the floor,
it will burst into flames before it hits the floor,
because it reacts with the water in the air.
Today I'm going to show you how to make a Potassium mirror.
We will just fish out a nice little bit of Potassium.
It's stored under mineral oil, because it reacts with water
over time. So it's quite malleable stuff.
It's a little bit like if you imagine cutting Blu Tac.
It's quite soft.
And it starts you see, it's starting to go a little bit
already. Tarnishing a wee bit. So we can just
manipulate it like that, and we are gonna pop it
into our ampule, and we are gonna evacuate it now.
I'm gonna remove all of the atmosphere,
from this ampule.
OK, we've done that because the, the boiling point of Potassium
under one atmosphere is over 700 degrees C. Which is pretty high.
It's too high for the glass to tolerate.
If I heated it up to that temperature the glass would start to soften, melt.
So by evacuating it, we remove all of the atmosphere which is keeping
the boiling point as high as it is. So it lowers the boiling point
much lower. So it starts to drop into the range
of water.
OK so we are just going to the blue flame,
which is the nice hot flame.
And we just keep on gently warming it.
And at some point, it will melt.
Just enough that you will start to see bubbles
of Potassium just jumping out of this thin oxide layer,
which is coating it at the minute. Now it's starting to form.
So the reason we do it like this is that we end up with a
large surface of Potassium, so it's excellent for
keeping our solvents dry.
So what we've got now, is we've got the ampule,
and all the way up here, this is literally a mirror
of very thin Potassium.
Potassium is very important. Our bodies contain quite
a lot of Potassium. And it's in all sorts of
biological material. If you burn
garden rubbish, in the ash that you get in the end is Potassium,
which is presumably why it's called Potash.
So as Neil quite literally wets the wall,
to get rid of all the un-reacted Potassium.
Wicked.
One of my colleagues who used to work with it,
described it as evil.
Captions by www.SubPLY.com