Explorit: Chemistry is behind winter’s frost

By Lisa Justice

Special to the Enterprise

The grass is white and crunchy, the sidewalk slippery and the car windows opaque. The frost has come. But what comprises this icy coating is a beautiful chemistry-induced wonder of nature!

Frost happens when humid air gets so cold that it can’t hold water anymore. When that happens, the water condenses and gets deposited on the ground or other surface.

But frost is special because it never passes through the liquid phase; it goes straight from a gas to a solid. Any water that was already on the ground and just freezes isn’t frost. The important difference is shape.

What sets frost apart from other icy formations is its crystal shape. Crystals can come in different sizes and be made of different materials, but they all have atoms that are arranged in regular, repeating geometric patterns. So no matter what a crystal is made of, it will have smooth, flat sides and fine points on the ends.

Take a morning stroll around your neighborhood and get a good look at the frost you find in different places: on a plant, on the ground or hanging from a roof. Use a magnifying glass to see the frost crystals up close.

How many crystal shapes can you find? How big are they? In what places do you find the most crystals or biggest crystals?

If you just can’t get enough crystals, there’s no need to wait until the next frost. You can make some crystals in a cup with a little chemistry.

You’ll need: two Styrofoam cups, a charcoal briquette, measuring spoons, salt, water, ammonia, liquid laundry bluing (available at a drug store), food coloring and an adult to help you work with chemicals safely.

Start out by placing your briquette in the bottom of one of your Styrofoam cups. The cup will keep your crystals contained as they begin to grow.

In the other cup, combine five tablespoons of salt, five tablespoons of water, five tablespoons of ammonia and one tablespoon of liquid laundry bluing. Stir them all together, then pour them over your charcoal briquette.

Once you add your chemical mixture to your briquette, try not to move it around too much. These crystals will break easily and you won’t want to disturb them.

You can now add a few drops of food coloring. Adding drops of different colors will create a variegated garden of crystals.

Now, set your crystal garden aside, but keep an eye on it. The crystals will begin to grow in about 20 minutes, and can keep on growing for about two days.

As they develop, make note of what you observe. How big are these crystals? How many crystals are there in your cup? How are these crystals different from the frost crystals you’ve observed?

Explorit’s coming events:

* Winter break: Explorit’s Beyond the Table exhibition will be open from 1 to 5 p.m. Saturday and Sunday, and on the Martin Luther King Jr. holiday on Monday, Jan. 21. This Saturday and Sunday, visitors may make fingerprint corn cobs.

* Fun on the Farm: Join us every Saturday and Sunday in January for a special farm activity. It’s free with paid admission to the regular exhibition.

— Explorit Science Center is at 3141 Fifth St. in Mace Ranch. For more information, call 530-756-0191 or visit www.explorit.org