We are planning a crystal making competition for Science Week this year. I have a couple of questions for those of you who know so much more about these things than I do.
a. Does anyone know of a source of large amounts of potash alum (at least 3kg) at a reasonable price?
b. Does anyone have any brilliant ideas for something beyond the usual copper sulfate/alum crystals?
I know there will be someone out there who has the perfect answer for me. You guys always do!
The answer to both might be contact the Double Helix guys in CSIRO Canberra. They conducted a crystal growing competition a number of years ago, and supplied schools with quatities of Alum, so I presume they know where to find it cheaply.
Checked out the CSIRO website and had a bit of a play around with various substances. We finally settled on the good old copper sulfate crystals. You can't really beat them for colour, speed of formation and shape. Even though we see them all the time the kids are still impressed by them. And it is available very cheaply from rural suppliers. Believe it or not they put it in horse feed or something? I can't remember but it sounds very unappetising.
No you cant beat the copper sulphate crystals, we are lucky here in Mount Isa, we have a copper sulphate producing plant, so I was able to get buckets of the stuff free from the kind people there . Over time we made some huge crystals and I spent lots of time making sat'd CuSO4! The depleted solution the crystal grows in can be recycled too.
I have tried many differnt types that are not overly haradous to try and get a range of crystals shapes and sizes. Some are better for growing large crystals such and the copper sulphate (dont forget to acidfy it with sulfuric conc too ). It will depend on weather you are seeding your crystals or just growing lumps of them.
magnesium sulphate (epsom salts) crystals are fairly easy to grow but they tend not to get over sized. So too for Potassium sodium tartrate, I have used Potassium ferricyanide , copper acetate monohydrate and calcium copper acetate - but again more for the different crystal structures than size.
As far as getting large quantities of any chemcial for your crystal growth i think a lot depends on where you live and if you have industry about i guess. I can not helpyou with that i am afraid.
Thank you for your contributions. We have settled for copper sulphate and bought some from our local produce store for $4.50 per kg. Probably not of the standard required for senior chemistry experiments, but fine for making crystals and the usual 'bucket chemistry' we conduct in the junior school. I've had great fun experimenting and trying to grow good crystals to demonstrate to the students. I look forward to checking out my crystals every morning when I walk into the prep room. Sometimes huge growth and sometimes not, depending when I replenish my solutions.
. Over time we made some huge crystals and I spent lots of time making sat'd CuSO4! The depleted solution the crystal grows in can be recycled too.
