Crystals

[Mudman]

Can anyone tell me how you make the Crystals that we got taught about at school? I remember something about jam jars, pencils and some blue liquid... But the rest's gone..

[foulecamp]

The usual way was with copper sulphate solution, which you put in the jamjar, usually with a few crystals to seed it. You then put a piece of wood or a pencil and left until until crystals started to grow.

[Mudman]

Sorry my friend.. That confused me more than school did.

[brachiopod]

Aye, a saturated solution of copper (II) sulphate.

If made saturated at high temperature ( ie. close yo boiling), then as it cools, it becomes super-saturated.

This is a (fairly) stable state unless you add something it can crystallise on - called a nucleus of crystallisation. In our case, we normally dip a small crystal of copper (II) sulphate into the saturated solution, suspended from a bit of cotton tied to a pencil - et voila, your CuSO4 crystal grows.

[Mudman]

Thanks for the info. Is the procedure the same for Iodene crystals?

[aka estie]

And you can do the same thing with a saturated sugar solution and make rock candy :-)

http://www.exploratorium.edu/cooking/candy/recipe-rockcandy.html#

[markja]

anyone able to help with beer crystals? or is it still the pub?

[Hamish]

There are loads of differnt ways to grow crystals, the one you would choose would depend on how big you want the crystal to be and what the material it. The most common way is to make a saturated solution of the material in a suitable solvent and then let the solvent evapourate off - this gradually produces a super-saturated solution and therefore results in crystal growth.....Sounds like you are remembering copper sulphate.

[Scotman84]

We did it with Potassium Permanganate, which is purple.