Crystalliasation

[hel]

Hi All,

Our year 7's are doing their famous crystallisation prac with copper sulphate & alum. Every year we have beakers with crystals adhered to the glass. Does anybody have an easy way to remove the crystals?

Cheers,
Hel

[dime]

I just soak in water - or maybe rinse under hot tap. Don't remember having too many problems.

[Slartibartfast]

I agree with the above, just rinse, don't force the crystals and leave to soak overnight if your not in a hurry to re-use the glassware.

[J]

Hot water usually loosens them up without too much effort.


Julie

[dolphinscales]

Use plastic take away containers??

[Jen1]

If the kids haven't filtered their copper sulphate solution very well, then a brown tinge can develop on the glass. I have a supply of hydrochloric acid that I use to rinse them and they come up beautifully. The acid can be reused many times but I wouldn't use it for anything else.
Cheers
Jen

[sandyd]

Hi,

We use plastic drink tumblers and find that this is much easier with the cleaning.

Sandyd

[Lyn]

Did this prac only once using beakers to crystallise copper sulfate/alum solution. Told teachers afterwards that they would be using disposable plastic petri dishes to recrystallise the solutions. Students let their solutions cool a little before pouring liquid into the petri dishes. The results are good and we save the best samples of crystals. Recycle the other dishes for a variety of uses.
Lyn.

[hel]

Thanks everyone. The plastic tumblers & petri dishes sound like a good idea for the future.