Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: IzzieC on 08/05/2018 15:50:22

Title: How does freezing and warming water change its properties?
Post by: IzzieC on 08/05/2018 15:50:22

Deon asks

"There's a trick of placing a bottle of water in a freezer and taking it out while the water is still liquid but very cold... When you bump or shake the bottle the water, ice will form. BUT if I completely freeze the water and then leave the bottle water outside till its warm, when I then place the same bottle back in the freezer for the same amount of time, I cant repeat the trick. Any Idea why?"

Can you help?

Title: Re: How does freezing and warming water change its properties?
Post by: Kryptid on 09/05/2018 02:55:10

Did you try this for yourself? Maybe it was just a fluke. Perhaps you should try it with different bottles several more times in order to establish that something more is actually going on. I don't see why you shouldn't be able to supercool the same water twice.

Title: Re: How does freezing and warming water change its properties?
Post by: evan_au on 09/05/2018 09:25:41

It is called supercooled water, and it only works if the water has no impurities like dust which will act as a nucleus for ice crystals to form at 0C.

Some nice videos here:
https://www.wikihow.com/Supercool-Water

Title: Re: How does freezing and warming water change its properties?
Post by: Bored chemist on 09/05/2018 20:21:42

One possible factor is that, when the water freezes, it will no longer dissolve the minerals etc that are present in it, and these will come out of solution as (tiny) crystals.
Those may act as "dust" to nucleate freezing on subsequent occasions.

Title: Re: How does freezing and warming water change its properties?
Post by: chiralSPO on 09/05/2018 22:11:24

The expanded frozen water may also introduce defects into the plastic bottle, which will act as nucleation points on successive freeze cycles.