Science Rules!	Don't Be Too Flaky
	Summary: The density of water, ice, and snow aren't the same even though all three are composed of H2O. In this experiment we'll measure the relative densities of these three substances. After you're done you can submit your results to us and they will appear here on our web site along with data contributed by other students all over the world!

I. JUST THE FACTS
Snowflakes are formed by the freezing of water vapor in the air. Layers of snowflakes on a surface, such as the ground, are simply called snow. Snow is mostly a combination of snowflakes and air. The amount of air that snow contains affects its volume (the amount of space it takes up). When snow melts, the trapped air is released. Thus, the volume of snow is greater than the volume of the liquid water it forms when melted. Not all snow is the same, and snow is not the only form of frozen water. Ice, sleet, and hail are also mostly a combination of frozen water and air. Let's compare the properties of ice and snow around the world, and at the South Pole.

Note: if a non-metric measuring cup is used for this activity, fluid ounces can be converted to milliliters using this relationship: 1 fluid ounce = 30ml. However, strictly speaking 1 fluid ounce = 29.573730ml, but we will use the approximation of 30ml= 1 fluid ounce for this activity. Whole number estimates of other relationships between metric and English measurements are also used, such as 1 quart = 1 liter, thus 1 cup =250 ml.

II. DON'T GET HURT / WATCH OUT!
Although snow and ice are very common materials, caution should be taken to prevent possible frostbite or cuts on the hand from jagged edges of ice that may be mixed with the snow. If you use kitchen utensils in the lab, be careful to make sure that they do not come in contact with materials that will contaminate them and make them unsafe to use with food.

III. WHAT'S UP? How does the volume of snow compare to the volume of liquid water that the melted snow forms? IV. WHAT DO YOU THINK? Make a guess about the amount of water you think a cup of snow will form when melted. Half as much? One-third as much? How much?

V. STUFF pencil ruler 1 sheet of paper permanent marker three (3) 10-oz (~300ml) clear plastic drinking cups (We suggest using 10 oz. clear plastic picnic cups that come from the same package, although other size cups will work. You need three because we will be finding average values) tap water volume measuring device ( graduated cylinder or metric measuring cup 750 ml (3 cups) snow (use shaved ice, crushed ice or accumulation of frost from a home freezer as alternatives if snow is not available.) spoon

1. Use the pencil and ruler to prepare a data table on the paper similar to the one in Scoreboard below.
2. Near the bottom edge of each cup, use the pen to label the cups A, B, and C.
3. Put 250ml (1 cup) of unpacked snow into each cup. Use the spoon to help remove the snow from the cup, but take care not to press the snow flakes together.
4. Record the volume of the snow, which should equal 250ml (1 cup), where you found it (your town, city, or locale), and a description of the snow (i.e. 3 day old snow) in the data table.
5. Draw a line and mark the snow level with an S (for snow) on each cup (all 3 should be the same).
6. Set the cups on a table indoors and allow the snow to melt.
7. When all of the snow has melted mark the water level on all three cups Sw (for snow water).
8. Pour the water from cup A into your measuring device. Record the volume of the water in the data table.
9. Determine the ratio between the volume of the snow and the volume of the water. Do this by writing a fraction with water volume as the denominator and snow volume as the numerator (ratio = Volume Snow/VolumeWater). Express the answer as a decimal by dividing the denominator into the numerator. Record the answer. (Note: the answer tells you how many time greater the snow volume is than the volume of the melted water it forms.)
10. Repeat steps 6,7 & 8 for cups B & C.
11. Determine the average ratio and record. Do this by adding the ratios and dividing by 3.

VIII. DO YOU SEE WHAT I SEE?
Submit the results of your experiment to us! As we collect data from students around the world we'll post the results here. To contribute your data simply fill in the blanks below and hit the "Submit" button.

Check out data already submitted. Inspect the data and answer the following questions:

1. How do your results compare with those from other areas?
2. If there is a difference, what could contribute to the difference?

---

Home | Experiments & Activities | Q&A | Travelogue | Pictures

HOME

CARA's research and education programs are supported in part by the National Science Foundation under a cooperative agreement, grant number NSF OPP 89-20223. © Copyright 1998,1999,2000 by Center for Astrophysical Research in Antarctica. This copyright applies to all web pages and images created by CARA. Check out CARA's organizational home page. Questions? Comments? email us at caraweb@astro.uchicago.edu Last modified Monday, 04-Dec-2000 16:35:09 CST http://astro.uchicago.edu/cara/southpole.edu/flaky.html