Density of Liquids

Patricia Doyle Peck School
3826 West 58th Street
Chicago, Illinois 60629
(312) 535-2450


1. Students will discover liquids have different densities.
2. Students will learn that the temperature of water affects its density.
3. Students will develop a definition for density of liquids.


For each group of 4-6 students:

balance cooking oil
3 identical clear plastic glasses water
1/4 cup measuring cup or graduated cylinder corn syrup
stirring rod or stick 2 one pint jars
food coloring 2 small aspirin bottles
paper towels lab sheets for each student
felt tip markers or crayons green liquid soap and alcohol


1. Using green liquid soap and alcohol, have the students measure 1/4 cup or
60 mL of each liquid and pour it into two separate plastic glasses.

2. Have students identify properties of these liquids. Do both liquids take up
the same amount of space? Do they have the same mass (weight)? How can we
find out? Have the students lift and feel. Next have them use the balance
to determine the mass of each liquid. Record the mass on the board and the
students will notice that the soap has more mass than the alcohol.

3. Introduce a new term density. When one liquid has more mass than another
and takes up the same amount of space, we say it has a greater density.

4. Next, have the students observe as you slowly pour the alcohol into the
glass with the soap. Did the soap and alcohol mix? Why or why not? The
soap and alcohol take up the same amount of space but the soap has more
mass. When we pour the alcohol into the glass of soap, the children observe
that the alcohol does not mix; it floats on top of the soap.

5. Set up stations for groups of 4-6 students. Using lab worksheet, each
student will determine the density of water, corn syrup and cooking oil.
Students will weigh and record the mass of 60mL of each liquid. Next they
will add 3 drops of food coloring to the glass of water and stir. Then they
will pour the water slowly into the glass of oil. Does the oil and water
mix? Which is denser? Finally, they will carefully pour the syrup slowly
down the side of the glass containing the water and oil; set the glass flat
and observe which liquid is the densest.

6. To demonstrate that the temperature of water will affect its density, have
the students fill a small bottle nearly full with hot colored water.
Holding their finger over the mouth of the bottle have them slowly lower the
bottle into a larger jar of cold water. When the students slowly remove
their fingers from the bottle, they will observe that the colored hot water
floats. Reversing the experiment and putting the cold colored water in the
small bottle and the hot water in the larger jar will show that cold water
is heavier (denser) than hot water. As the water temperature evens, the
water mixes. Do hot and cold water have the same density? If not, which
is denser?


Have the students draw pictures and label what they observed in each of the

Extension Activity:

Find some small objects, for example, marbles, plastic pieces, paper clips,
styrofoam, aluminum and wood. Have the students predict on which layer each
object will float and then drop each object into the glass of layered corn
syrup, water and oil. Observe what happens.

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