Apr. 02, 2010

Let It Snow, Indoors!

by Lynn Brunelle

Click to enlarge images

Are you aching for snow with no chance of it in sight? Why not dabble in chemistry and make some beautiful crystals of your own? With stuff you already have around the house, you can whip up a batch of your own crystal snowflakes. They’re fun to make and they make really cool gifts.

What You Need

For the flake
White pipe cleaners (chenille twists)
Scissors
String
A pencil

For the crystal concoction
(If you want to make crystals quickly use a Borax solution—you can make cool crystals overnight. But if you don’t have Borax, no worries; you can use sugar. It takes a little longer but it works just the same.)
1 box Borax Laundry Booster (the 20 Mule Team brand works well but Boraxo soap will not work)
A wide mouth glass jar (such as a peanut butter or jelly jar)
Hot water
Food coloring - optional
Spoon

For the fabulous finished flake
Pretty ribbon

What You Do

For the flake

  1. Cut the pipe cleaner into three equal segments and twist the three pieces together at the middle to make a six-pointed “snowflake”.
  2. Tie one end of the string to one of the spikes.
  3. Dangle the snowflake in the jar. Tie the other end of the string to the middle of the pencil so the flake will hang about one half inch above the bottom of the jar. Pull it out and set it aside.

For the crystal concoction

  1. Have a grown-up help you pour boiling water into the jar to about one inch from the rim.
  2. Add the borax powder (or sugar) to the hot water a spoonful at a time, stirring until it dissolves. Keep doing this until it won’t dissolve any more—you’ll have some powder hanging around at the bottom of your solution. That’s OK: it means your solution is supersaturated.
  3. Add a few drops of food coloring, if you’d like to make colored crystals, and stir.
  4. Dangle your flake in the solution making sure it’s completely covered by liquid and let it still overnight.
  5. Check it in the morning. Has anything changed? How does your snowflake look? (If you used sugar instead of borax, you may need to wait a couple more days.)

For the fabulous finished flake

  1. Pull it out when it looks good and let it dry completely.
  2. Snip the string off, tie a pretty ribbon on the flake, and it’s ready.

What’s Going On?

Crystals are solids made up of molecules that line up in specific repeating patterns. Different kinds of crystals have different patterns and different shapes. Snowflakes are ice crystals and they always have six sides. Salt crystals are always cube-shaped. Borax is a crystal, too.

Borax powder dissolves in water. It seems to disappear, but the molecules are still there; they’re just separated by water molecules so you can’t see them. If you add borax to cold water until no more dissolves, you have a saturated solution. That means no more borax molecules can hang out between the water molecules--the solution is full. But when you add borax to HOT water a funny thing happens. In a container of hot water the molecules are moving around faster, so the spaces between are bigger and because the spaces are bigger, a lot more borax powder can dissolve and fit in.

So instead of a saturated solution, you made a SUPERsaturated solution. And as it cooled, the water molecules got closer together and there was less room for the borax molecules. The borax molecules came together, lined up and formed into crystals. Since you had your pipe-cleaner snowflake shape in the cooling solution, the crystals formed all along the pipe-cleaner surfaces.

About Lynn Brunelle

The views expressed are those of the author and are not necessarily those of Science Friday.

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