Rainbow Density Lab

Name: ________________________________ Date: _________________ Period: ____________
Rainbow Density
I. Purpose Question: What is the relationship between a liquid’s density and the location it
appears in a column of liquid?
II. Hypothesis: _________________________________________________________________
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III. Materials:
apple 3 g Salt apple 3 100 mL Beakers
apple 75 mL Water apple Large Graduated Cylinder
apple Triple Beam Balance apple Small Graduated Cylinder
apple 3 50 mL Beakers apple Pipettes
IV. Variables:
a. Identify the Independent Variable: _________________________________________
b. Identify the Dependent Variable: __________________________________________
V. Procedure:
a. Day 1:
Solution Chart
Solution Salt Water
A 0.5 g 25 mL
B 1.0 g 25 mL
C 1.5 g 25 mL
i. Obtain three beakers, one container of salt, one triple beam balance, and
one graduated cylinder. Label the beakers A, B, and C.
ii. Dry the first beaker and take its mass. Record the mass of the beaker in
the data table located in the data section of this lab.
iii. On the data table, add the numbers from the columns “Mass of Salt” and
“Mass of Beaker” for the desired solution and write the answer in the
column “Mass of Salt and Beaker.” This calculated mass is the mass you
wish to obtain when you add the salt.
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iv. Add the amount of salt specified in the Solution Chart to the beaker.
Adjust the triple beam balance until the desired mass is obtained (This is
the mass calculated in step ii).
v. Use water from your sink and obtain 25 mL of water, measured in the
graduated cylinder.
vi. Pour the 25 mL of water into the beaker that has the salt in it. Stir the
solution until the salt is completely dissolved.
vii. Mass the beaker with the salty water in it. Record the mass in the data
table.
viii. Repeat steps ii-v for Solution B and Solution C, using the different beaker
each time.
VI. Discussion Questions:
a. Day 1:
i. How do the volumes of the solutions compare to one another? Does adding
different amounts of salt increase the volume at different levels? ___________
___________________________________________________________________
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ii. How do the masses of the solutions compare to one another? ________________
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iii. Calculate the density of each solution. Find the mass of the solution from the
Data Table, in the column labeled “Mass of Salt and Water.” Find the volume
of the solution from the “Solution Chart” on page 1.
Solution Density (Density= Mass/Volume)
A
B
C
iv. Predict what you think will happen if the solutions were put into a test tube.
If Solution A was red, Solution B was yellow, and Solution C was blue, draw
what you think the test tube would look like. ____________________________
___________________________________________________________________
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VII.
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Procedure
a. Day 2:
i. Obtain 10 mL of Solutions A, B, and C. Measure out the 10 mL in the
smallest graduated cylinder then three small beakers.
ii. Pipette 2 full pipettes of each liquid into one test tube as instructed by
your teacher at the beginning of the period. Do this in the following
order: Blue, Yellow, and then Red.
iii. Make a drawing of the test tube once you have completed your pipetting (do
this in the space provided in the data section of this lab packet).
VIII.
Data:
a. Data Table:
Solution Mass of Salt
Mass of
Beaker
Mass of Beaker
and Salt
Mass of Beaker and
Salt and Water
Mass of Salt
and Water
A
0.5 g
B
1.0 g
C
1.5 g
b. Test Tube Drawings
Solution A (Red) Solution B (Yellow) Solution C (Blue)
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IX. Discussion Questions:
a. Day 2:
i. Did your result turn out as you expected? (See Day 1 Question 4) Explain
your answer. _____________________________________________________
________________________________________________________________
________________________________________________________________
ii. List the layers, by color, in the order of least to most dense.
1.
2.
3.
iii. If the volume of each layer is the same, explain why their densities are
different. ________________________________________________________
________________________________________________________________
________________________________________________________________
iv. Predict what you think would happen if you inverted the test tube. Then,
invert the test tube. Explain what you observe and why it happened. _____
________________________________________________________________
________________________________________________________________
X. Conclusion: (State if your hypothesis was right, why or why not? Use data to support
your answer. Be sure to answer the purpose question and make a short summary
statement about the results of the lab.)
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