Growing Crystals
For an extra credit project I was assigned through my chemistry class at school, our class had the opportunity to grow crystals. Were were able to make them out of whatever we wanted and the better the crystal, the more points we would get. I did lots of research into the best materials, methods, and kinds of crystals to make and how to do it and decided to share my results and experiences for other people to use.
I used a chemical called Potassium Ferricyanide to make my crystals (Chemical formula K3[Fe(CN6)] ). It is a dark red compound that comes in the form of a red powder or small red crystals. Despite its name containing the word "Cyanide," it is non-toxic as the cyanide ion is very strongly bonded to the Iron and it requires either extremely high temperatures or contact with an acid in order to decompose into a dangerous compound, neither of which will be involved in growing a crystal.
There are many other alternatives available besides this chemical for growing crystals, many easily available cheaply and easily from places like convenience stores. Some of the most popular compounds are Copper Sulfate, Alum, and other common substances such as Sugar and Table salt. The difficulties of growing the crystals varies depending on the type of substance used to grow them; some are more difficult than others. Alum and Copper Sulfate are generally seen as being some of the easiest crystals to grow, while table salt can be tricky to get going right.
I used a chemical called Potassium Ferricyanide to make my crystals (Chemical formula K3[Fe(CN6)] ). It is a dark red compound that comes in the form of a red powder or small red crystals. Despite its name containing the word "Cyanide," it is non-toxic as the cyanide ion is very strongly bonded to the Iron and it requires either extremely high temperatures or contact with an acid in order to decompose into a dangerous compound, neither of which will be involved in growing a crystal.
There are many other alternatives available besides this chemical for growing crystals, many easily available cheaply and easily from places like convenience stores. Some of the most popular compounds are Copper Sulfate, Alum, and other common substances such as Sugar and Table salt. The difficulties of growing the crystals varies depending on the type of substance used to grow them; some are more difficult than others. Alum and Copper Sulfate are generally seen as being some of the easiest crystals to grow, while table salt can be tricky to get going right.
Getting Started
The first thing you'll have to do is get the ingredients necessary to make your crystal. You can use one of the chemicals from above or another chemical that forms crystals - just make sure it's non-toxic and easy to use. You can get them online or at chemical supply stores. However, stuff like Alum and Salt can be picked up from a local food center. You'll need enough to fully saturate an amount of water to fill about 4-6 inches of the bottom of a jar; About 100-200 grams should be enough for most purposes. You'll also need a jar or other container for making the crystals in; it should be large enough to hold all the water and chemical you'll be using and have a small enough top to hang a string out of.
Creating a Saturated Solution
The most important part of growing crystals if the preparation of the saturated solution. In case you didn't know, a saturated solution is a solution in which the maximum amount of solute, or dissolved material, has been reached and no more can dissolve. You know a solution is saturated when there is solid solute on the bottom of the jar that will not dissolve, even after stirring and time left sitting.
When making a saturated solution, it is important to not make the mistake I made and add too much water to start off with. If you do this, you'll end up not having enough of your chemical to form a saturated solution and thus crystals will not form. I recommend adding small bits of water to the jar along with small bits of the chemical being dissolved until it no longer dissolves, then adding a bit more and a bit more until there's just a tiny bit of the chemical you need left on the bottom. Again, you know that a solution is saturated and ready for crystal growing when the chemical you add no longer dissolves.
When making a saturated solution, it is important to not make the mistake I made and add too much water to start off with. If you do this, you'll end up not having enough of your chemical to form a saturated solution and thus crystals will not form. I recommend adding small bits of water to the jar along with small bits of the chemical being dissolved until it no longer dissolves, then adding a bit more and a bit more until there's just a tiny bit of the chemical you need left on the bottom. Again, you know that a solution is saturated and ready for crystal growing when the chemical you add no longer dissolves.
Starting your Crystals
Once you have a saturated solution, you have to grow some seed crystals to act as nucleators for the larger crystal(s) you will be growing. A seed crystal is a small crystal that the larger crystal grows on. To make them, you need to add a small bit of water and the chemical you're using to grow the crystals to a small dish or saucer. Form a solution and wait for the water to dissolve. As it dissolves, small crystals will form on the bottom of the dish. These are the seed crystals. You can then tie a small string or better yet some fishing line around it and use that to grow your larger crystal.
Tie the other end of the string your seed crystal is attached to to a pencil or other similar object and set it over the opening of the jar you will be using to grow the crystal containing the saturated solution. The seed crystal should be suspended within the solution in the middle, fully underwater and not touching any of the jar's sides or the bottom. Place the jar in a place with stable temperatures (so that the solution inside doesn't change in temperature much) and cover it with something like a coffee filter to keep dust and other stuff out of it. Make sure that water can still evaporate, though, so don't completely cover it and make sure air has space to circulate. Then, you just have to leave it and wait.
As time goes by, the seed crystal will begin to accumulate more and more material and grow larger and larger. Check it every few days to make sure it's still suspended in the middle of the fluid and move it down as the water level drops over time. Once it has grown to a level that you are happy with or the water level gets low enough that it can't fit anymore, you can take it out and let it dry. The string will probably be inside of it which is fine; you can then cut it or leave it in and hang it from the ceiling or something. Some kinds of crystals decompose or disintegrate in the air and must be sealed with a lacquer or other sealant. Make sure you know about this for your particular kind of crystal before growing.
Tie the other end of the string your seed crystal is attached to to a pencil or other similar object and set it over the opening of the jar you will be using to grow the crystal containing the saturated solution. The seed crystal should be suspended within the solution in the middle, fully underwater and not touching any of the jar's sides or the bottom. Place the jar in a place with stable temperatures (so that the solution inside doesn't change in temperature much) and cover it with something like a coffee filter to keep dust and other stuff out of it. Make sure that water can still evaporate, though, so don't completely cover it and make sure air has space to circulate. Then, you just have to leave it and wait.
As time goes by, the seed crystal will begin to accumulate more and more material and grow larger and larger. Check it every few days to make sure it's still suspended in the middle of the fluid and move it down as the water level drops over time. Once it has grown to a level that you are happy with or the water level gets low enough that it can't fit anymore, you can take it out and let it dry. The string will probably be inside of it which is fine; you can then cut it or leave it in and hang it from the ceiling or something. Some kinds of crystals decompose or disintegrate in the air and must be sealed with a lacquer or other sealant. Make sure you know about this for your particular kind of crystal before growing.
Common Problems
Crystal growing is a sensitive process prone to difficulties and problems. There are many things that can go wrong. One of the most common problems is when the seed crystal is put into the solution inside the jar, it dissolves. This means that the solution wasn't saturated and that you need to add more of your chemical. If there is some solid on the bottom but it still dissolved, make sure you've given it time to fully dissolve and stir it for a while until it all fully dissolves; then add more until it becomes truly saturated.
If you get small crystals growing on the side of your large crystal, called parasite crystals, you can either try to remove them (although this is dangerous and risky) or just leave them and deal with a slightly malformed crystal. If you do chose to remove it, do so VERY carefully, doing as little damage to the larger crystal as possible. Generally, the pocks will fill themselves in with more time but will probably leave some discoloration in that area of the crystal.
If you get small crystals growing on the side of your large crystal, called parasite crystals, you can either try to remove them (although this is dangerous and risky) or just leave them and deal with a slightly malformed crystal. If you do chose to remove it, do so VERY carefully, doing as little damage to the larger crystal as possible. Generally, the pocks will fill themselves in with more time but will probably leave some discoloration in that area of the crystal.