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Grow Large Crystals
Once again, we need to prepare a concentrated copper sulfate solution as before, but in a much larger quantities. Make about half a beaker (250 ml volume size) of hot saturated copper sulfate solution. Use the glass rod to stir the solution as you add the copper sulfate to the beaker. Continue to add the sulfate until a small quantity of undissolved sulfate remains at the bottom of the beaker.
During addition, heat the solution if necessary (but not boil) in order to maintain a hot temeprature. Pour the clear blue solution into a clean beaker or jam jar, being careful not to add any of the sediment, and allow to cool. If eventually some more small crystals form at the bottom when the solution is cooled, pour the solution into another clean beaker. Repeat this procedure until no crystal is formed.
Filter the solution if necessary to remove any dirt or impurity. At this stage you have prepared a concentrated copper sulfate solution at the room temperature.
Now, select a well-shaped copper sulfate seed crystal as mentioned from the previous page and tie it to a piece of cotton and then dangle it in the concentrated solution (see diagram below).
A copper sulfate seed suspends in the concentrated solution, by a support beam.
Cover the jar and leave it in a place where the temperature is even and there is no draft or dust. And yes, crystal is not a plant and it does not need light to grow. You can place the jar in a cupboard. The size of the seed crystal can grow quickly in all direction. The annoying part is that some of the cotton will be permanently trapped as the crystal grow.
Another way is to place the seed crystal (very gently) at the bottom of a container. In this way, the crystal need to turn over to a fresh face (side) on a regular basis, preferably once every day. This is rather tricky because as the crystal knock against the glass during turning, it may deposit tiny fragments that can act as seeds for
small crystals to form. It is easier to turn the crystal, in a more gentle way, by using two flat wooden spatula (eat two ice creams to get them!). If any small crystals form in the solution pour off the liquid into another container and replace the large crystal. Diagram below shows another example setting for the crystal growth.
Here, a petri dish is used instead of a jar as it is easier to turn the large crystal in a wider opening and swallower solution. The dish cover can also use as an effective protection to keep away dusts or other impurities. Note that the crystal growth rate is smaller when compare with the method of crystal suspension. In both cases, more solution will
have to prepare and larger containers will be needed as the crystal grows larger.
In the next page, we show the photos of large copper sulfate and potassium sodium tartrate crystals.
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