When you think of winter, you might picture some beautiful, snow-covered trees.
In this month's blog, you'll use the science of capillary action and evaporation to create some "snow"-covered trees of your own. So even if there's no snow where you live, you can make some indoors to set on your windowsill!
NOTE: Setting up the lab will only take about 20 minutes, but you'll have to wait a few hours or overnight to see the final results.
WARNING: Ammonia fumes are toxic! Ask an adult for help and work in a ventilated area. (You can choose to omit ammonia from the experiment - it will just take a bit longer to develop and the results will be a little less dramatic.)
WARNING: Bluing agent can stain your clothes, so be careful! (It will not stain your bowl however, as long as it's nonabsorbant - plastic, glass, or glazed ceramic work great!)NOTE: Plain, noncorrugated cardboard works best, but in a pinch you can use something with a waxy side (like a cereal or cracker box). We used the paperboard sheet from a pack of construction paper.
If you don't see crystals on the outer branches, this may be because the cardboard has dried out. You can use a dropper to draw up some of the liquid from the bowl and squirt it on the drier places on your tree during the evaporation phase.
If you made your tree larger than about 2.5 inches, there may not be enough solution to be effective. Try doubling the solution ingredients, or making a smaller tree.
What's going on?
Did you see a bunch of "snow" crystals on your tree? How did that happen? Well, there's a couple different scientific concepts at play - capillary action and evaporation.
In this experiment, the liquid was pulled up into the cardboard tree by the process of capillary action. Capillary action is the climbing ability of liquids.
For example, water can crawl up tiny tubes that are present in different materials. It does this naturally without any help. Capillary action is how plants deliver water from the soil to their leaves! It's also how water is sucked up into a paper towel. If you are interested in experimenting more with capillary action, check out this capillary action experiment!
Evaporation is also at work here. You may know that water can undergo evaporation, which is the process of changing from a liquid to a gas, (or water vapor). Adding ammonia to the liquid in this experiment speeds up the rate of evaporation.
During the night, the water and ammonia liquid evaporated, leaving behind the salt and the small particles from the bluing agent. Together they created the beautiful "snow" crystals you see on your tree!
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