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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Zyphus on October 22, 2013, 02:51:41 PM

Title: Growing a single clear Copper(II)Sulfate crystal
Post by: Zyphus on October 22, 2013, 02:51:41 PM

In our lab we've grown seed crystals by heating our solution to 80 degrees and transferring our solution to a watch glass.
Quickly many, MANY crystals started forming, (too??) quickly forming clusters. We managed to isolate a single crystal and tie it to a piece of nylon thread. Then we suspended the crystal in a test tube. Today, one week later we found many clusters forming around the not of the thread on top of a beautiful crystal.
We tried to clear the clusters from our main crystal, but it got a bit damaged. Then we made a new solution and put the crystal back in.

Now I'm afraid that new clusters will form on the damaged parts of the crystal, we still have some lab time left to start over. But this time our experiment should be spot on. Does anyone have tips to get a perfect single crystal (size is less important), or some mistakes we made in our experiment?

- do we need to heat our solution? (in my opinion, room temperature should be ideal, according to others it needs to be heated)
- how do we suspend it without creating clusters around the knot?
- any other useful tips?

Title: Re: Growing a single clear Copper(II)Sulfate crystal
Post by: Arkcon on October 22, 2013, 03:22:40 PM

Basically, growing large single crystals is more an art than a science.  Once they are 1 mm in size, pure and clear, they are adequate for x-ray crystallography.  The several cm sized ones suitable for display take even more than science or  art -- they take luck.  However, some things to help

-- You have to try to grow slowly.  If a warm saturated solution grows many crystals when taken to room temp, then a hot saturated solution may grow bigger crystals when cooled only to warm.

-- You will have to experiment with different strings, nylon fishing line is a good choice, assuming such things still exist.  Whatever you choose, you will still end up with a string embedded in your crystal.

-- If you can get crystals to grow in some sort of gel, you will have a string-less, 3 dimensional "crucible", that slows diffusion, and resists temperature changes.  That's a little bit hard to swing however.

Title: Re: Growing a single clear Copper(II)Sulfate crystal
Post by: magician4 on October 22, 2013, 05:57:24 PM

in addition:

try to cool down slowly , and without any tremor if possible: the less oversaturated the solution is at any given moment , and the less micro shockwaves there are, the more perfect the crystalls will grow.
with really, really a lot of time involved, they might as well become gigantic:
(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fnews.nationalgeographic.com%2Fnews%2F2007%2F04%2Fphotogalleries%2Fgiant-crystals-cave%2Fimages%2Fprimary%2Fcrystal-cave-1.jpg&hash=e33a50c67ef4fd25f607183fe18c91966e5e28e2)
(Gypsum crystalls in a natural cave , from: link  (http://news.nationalgeographic.com/news/2007/04/photogalleries/giant-crystals-cave/))

regards

Ingo

btw.: you won't grow copper(II)sulfate crystalls this way, but copper(II)sulfate pentahydrate crystalls instead

Title: Re: Growing a single clear Copper(II)Sulfate crystal
Post by: Zyphus on October 23, 2013, 08:16:25 AM

thanks for the reply

Title: Re: Growing a single clear Copper(II)Sulfate crystal
Post by: curiouscat on October 23, 2013, 09:00:14 AM

That's a cool photo.

First I thought it was fake.