Lab: Density
Learning Targets:
• I can obtain measurements with a triple beam balance and a graduated cylinder.
• I can use graphical data analysis techniques to demonstrate that density is the slope of
the line on Mass vs. Volume line graph.
• I can write a concise, accurate lab report to explain my findings (do not include this learning target in
your lab report).
Vocabulary
cubic centimeter
mass
meniscus
volume
density
mean
milliliters
accuracy
grams
median
mode
precision
Purpose: By finding the mass and volume of a group of identical paper clips, the density of a
single paper clip can be determined using the formula for density.
Equipment:
Graduated Cylinders
Triple Beam Balance
Thread
Paper Clips
Calculator
Water
Graph paper
Procedure:
Mass of a paper clip.
By using multiples of six (6) clips measure the mass of each collection of clips. Remember
that each member of the group must measure each collection of clips. As a group you
should reach a consensus on each value. Keep track of your significant digits and place
units on every measurement! Be certain that you only use LARGE paper clips. You need to
create a copy of this chart on graph paper to record your data.
Number of Clips
6
18
24
36
48
60
Reader #1
Reader #2
Reader #3
Average Mass*
*Note: You are reading the mass measurements together to
1st – learn how to read a triple beam balance
2nd – build a consensus regarding the most accurate reading
Therefore, you may not need to calculate the ‘average’. By coming to a consensus, you should all agree on the mass reading.
Volume of a paper clip.
By using multiples of six (6) clips measure the volume of a collection of clips. Also, note that the all
clips must be TOTALLY submerged before you read the volume of water. Since your graduated
cylinders are marked off in 1 ml increments, you can only estimate one (1) decimal place.
Remember that each member of the group must measure each collection of clips. Also, remember
to keep track of your significant digits and to place units on every measurement!
Link the paper clips into chains of six. Create a loop in a length of thread; hang the clips from the
loop. Completely submerge the sets of 6 paper clips at a time in the water and record the new water
level. Take a before and after photo for one of your volume measurements.
DO NOT DROP THE PAPER CLIPS INTO THE WATER.
Always suspend them from the loop of thread.
Then, subtract the original water level from the new water level to determine the amount of water
displaced by each collection of paper clips. After each group member has made his/her
measurement, calculate the average change in water volume for each group of clips. ALERT: Since
1 ml of water is displaced by each cm3 of solid paper clips, this average value needs to be
expressed in cm3.
Original water levels: Start as close to 85.0 ml as possible. You need to create a copy of this
chart on graph paper to record your data.
Number of
Clips
Reader #1
original water _____ ml
new water
net water
level
displaced
Reader #2
original water _____ ml
new water
net water
level
displaced
Average
Volume of
Clips
6
18
24
36
48
60
Graphical Analysis.
Graph your data by hand. Neatness is vital on graphs to
insure the data is represented accurately.
You will have 10 coordinate pairs to include on your graph as
( volume , mass ). Create a data table for the coordinates.
Be certain to follow the graphing basics in your BOOK OF PHYSICS.
When your graph is finished, be certain that any points that are obviously out-of-line have been
rechecked for accuracy -- either in measurement, or for a mistake in graphing.
Write the equation for a line: mass = (density)(volume)
Your group’s density estimate for the paper clip is represented by the value of the slope of the line
on your graph
Your DENSITY LAB report:
Your grade on this lab will be based on the quality of your final report. As you write your
report, imagine that the reader has not done this lab and does not know what you know about
density. Your report should inform the reader about the lab and explain the concept of
density. This report must include:
• A brief introduction of the lab (approximately 50 -100 words)
o Your introduction should include the lab’s purpose followed by a brief description
of the way you conducted the lab.
• Photos or drawings of the mass and volume measurements
o Be sure to include brief captions on the photos to explain to the reader what the
photos show.
• Data tables (three of these)
• Mass vs. Volume Graph
• Density calculation from graph slope.
• Conclusion: Evaluation the quality of your group’s data (see notes that follow).
With the exception of the first and last bullets, you should have complete all of the items
mentioned above as we completed the lab.
Notes on Conclusion (the last bullet point) :
To evaluate the quality of your group’s data, you will compare your paper clip density to the
‘accepted value’ provided in class.
You need to discuss the accuracy and precision of your group’s data.
Refer to your BOP for a refresher on accuracy and precision.
NOTE: Remember that you are in a Science class. It is not appropriate to say ‘I think our
data was really precise because we were careful and did a good job.’ In Science, you must
prove your claim by using data (numbers) to back it up.
Density Lab: Scoring Rubric
Section
Introduction
__/15
Images/photos
__/10
Data tables
__/15
Graph
Grading parameters
Purpose stated accurately;
description informs reader of
the steps to complete the lab
and integrates the learning
targets into the explanation of
the steps.
11-15
Both photos are included and
depict mass & volume
measurements; captions
provide reader with information
not included in the intro.
9 -10
Three data tables include
measured values; units;
sample calculation (where
applicable); Data tables are
accurately titled.
11-15
All elements of a quality graph
are included (BOP page 11);
coordinates labeled
__/20
Density
(using slope calculation)
__/10
Conclusion
__/15
Scientific
vocabulary
__/15
Comments:
Purpose stated accurately;
description informs reader of
most of the steps to complete
the lab and mentions learning
targets yet does not tie
learning targets to the data
collected.
6-10
Both photos are included and
depict mass & volume
measurements; captions are
accurate.
5-8
Three data tables include
measured values; units. Data
tables are accurately titled.
6-10
Minor errors on the graph;
Most elements of a quality
graph are included (BOP page
11); coordinates labeled
20
Density equation stated; slope
calculation completed with
work shown; data points are
based on the ‘best fit’ line.
UNITS ARE ACCURATE.
16 - 19
Density equation stated; slope
calculation omits work shown;
data points are not based on
the ‘best fit’ line.
UNITS ARE ACCURATE.
Lab’s purpose is restated.
Group’s density stated and
compared with the ‘accepted
value’ provided in class.
Accuracy and Precision are
addressed by citing data.
11-15
Student’s use of scientific
vocabulary was exceptional
and enhanced the overall
report.
Group’s density stated and
compared with the ‘accepted
value’ provided in class.
Accuracy and Precision are
addressed by citing data.
11-15
6-10
Student’s use of scientific
vocabulary was accurate and
clarified the overall report.
6-10
Purpose altered or
stated inaccurately;
lab description
incomplete; learning
targets incomplete or
unrelated to data
collection.
1-5
Purpose omitted or
altered; lab
description unclear
or omitted; learning
targets not included
or unclear
0
Photos or captions omitted.
0
Two of the three data
tables included with
measured values;
units.
Data tables omitted.
1-5
0
Major errors on the
Graph omitted or
graph; major
graphing errors that
elements of a quality
misrepresent the
graph are omitted
data
(BOP page 11).
1 -5
0
One or more omitted or inaccurate: Density
equation stated; slope calculation; data
points are based on the ‘best fit’ line.
UNITS ARE ACCURATE.
Two or more omitted or inaccurate: Lab’s
purpose is restated. Group’s density stated
and compared with the ‘accepted value’
provided in class. Accuracy and Precision
are addressed by citing data.
0
Student’s use of
scientific vocabulary
was attempted, yet
clarity was adversely
affected.
1-5
Student did not
consistently use
scientific vocabulary
0