Don't Be Too Flaky
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?
VI. JUST DO IT
- 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
VII. SCORE BOARD
- Use the pencil and ruler to prepare a data table on the paper similar to the one in Scoreboard below.
- Near the bottom edge of each cup, use the pen to label the cups A, B,
- 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.
- 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.
- Draw a line and mark the snow level with an S (for snow)
on each cup (all 3 should be the same).
- Set the cups on a table indoors and allow the snow to melt.
- When all of the snow has melted mark the water level on all three cups
Sw (for snow water).
- Pour the water from cup A into your measuring device.
Record the volume of the water in the data table.
- 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.)
- Repeat steps 6,7 & 8 for cups B & C.
- Determine the average ratio and record. Do this by
adding the ratios and dividing by 3.
Create a table like the one below and record your data.
SNOW / WATER DATA TABLE-1
Snow Sample Location
| A || || || |
| B || || || |
| C || || || |
Average Volume ratio snow/water =
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:
- How do your results compare with those from other areas?
- If there is a difference, what could contribute to the difference?
If the snow were fresh would the results be different than if it were old?
If you are in an area where conditions allow, wait for a new snowfall
and repeat the experiment. First use fresh snow, and then repeat again using
snow that has been on the ground several days (the longer the better);
or repeat multiple times with a different sample every day. Prepare and record your
data in a chart similar to the one shown here.
| Day 1 || || || |
| Day 2 || || || |
| Day 3 || || || |
| Day 4 || || || |
Average Volume ratio snow/water =