In our water cycle workshop we talk about 'Supercooled Water'

I've got a demo here for you that's great to try at home.

So, you may notice on those cold winter evenings people place salt

out on the streets and pavements, because salty water can go well below zero degrees

and remain liquid it freezes.

We're going to try and get a bottle of fresh water to get well below zero degrees C

but still remain a liquid.

For your super cooled water demo

you need lots and lots of crushed ice,

a small bottle of water

a beaker with round about 100ml of tapwater

plenty of table salt,

teaspoon, and a metal cylinder to place all of your ingredients inside.

First thing I'm going to do is to pour plenty of crushed ice

into the bottom of my metal cylinder then

I need five teaspoons salt to sprinkle around

I'm going to now place my small water bottle inside

Around that water bottle now i need to pack in

as much ice as possible.

Now, another 5 spoons of salt

Next, i'm going to take 100ml of water

and add 5 teaspoons of salt to this

Stir the mixture around

Now i'm going to pour this salty water all around the ice

around my bottle

Now, if you've got any room

add some more ice on top

What we do now is just sit and wait for a good 30 minutes

and then our supercooled water should be ready

The reason why i can get a bottle of fresh water below zero degrees without freezing

is because in our bottled water,

we have nonucleation points. A nucleation point is simply

any impurities inside that bottle of water which is going to allow

ice crystals to form around it. Now when I have my bottle of fresh water that is

liquid but below zero degrees, if i cause a disturbance

like pouring that water over an ice cube, I'm going to create many nucleation sites

and that liquid will turn to ice instantly.

it's been about 30 minutes now, so let's see if our super cooled water

is ready to make some instant ice

So there you go. Instant ice, fantastic experiment.

Why don't you try at home?