Sink or Float? Working with Densities
Project Overview
This Real World Learning Objective (RWLO) is aimed towards being applied in a
fundamentals or introductory chemistry course. Students should have prior
knowledge of unit conversion, definitions of mass, volume and density, and
should be introduced to Material Safety Data Sheets (MSDS).
The purpose of this RWLO is to have students perform conversions and
calculations and critically think about the concept of density. Through the use of
MSDS, students will find the density of various chemicals and apply their
knowledge about density to determine mass or volume in given problems.
Additionally, students will decide how to layer compounds in order to create a
“density” column.
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Student Learning Objectives
For this RWLO, the student will be able to:

Manipulate the density formula.

Determine the density of various compounds by finding Material Safety
Data Sheets.

Calculate mass given the volume and density.

Calculate volume given the mass and density.

Use density to determine which compound will “sink or float”.

Create a density column of common chemicals.
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Procedure
Time: Activity should take approximately a one hour class meeting.
Materials: Density worksheet, calculator, pencil, Internet connection, and basic
knowledge of search engines.
Prerequisites: A lecture on density should precede this RLWO. A computer lab
should be reserved so that students may find the MSDS sheets with provided
websites and through search engines such as Google or Ask.com. Students
should be shown how to locate the physical properties of chemicals on MSDS
handouts (section 9). It should be noted that many MSDS use specific gravity
rather than density. Therefore, students should be made aware of the term of
specific gravity and be told they may use that value to indicate density for this
purpose. For reference, please see the following website:
http://www.ilpi.com/msds/ref/density.html. Additionally, one free MSDS website
(www.chemfinder.com) requires a student to register. This should be performed
prior to the session.
Implementation: This RWLO can be used either in the classroom to further
explain the concept of density or it can be given as an outside of class homework
assignment as a reinforcement.
Steps:
1. Students should be given a brief summary of density and its related terms.
2. The density worksheet should be given to each student and students
should be paired into groups of two.
3. Students should be given approximately twenty minutes to find and record
data of requested densities as well as two densities from household
products from various websites containing Material Safety Data Sheets on
various chemicals.
4. For the other forty minutes, students will use the densities to perform
calculations and answer questions.
5. Each group should share one of their chemicals they found with the class
to make a hypothetical density column.
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Content Material
Sink or Float? Working with Densities
Density Worksheet
Part A: Revisiting Density: When chemists perform separations, looking at the
densities of chemicals are important. Density is expressed in terms of an amount
of mass per unit of volume a substance has, for example g per mL. The formula
for density is D = mass / volume.
Directions: Please read each question carefully. Complete each question by
showing your work and boxing your answer.
1. If you were asked to solve for mass given density and volume, what would the
formula now look like?
2. If you were given mass and density, how would you calculate volume?
3. If compound A had a mass of 5.6 g and a volume of 8.3 mL, what would be
the density in (g/mL)?
4. If compound B had a mass of 9.5 kg and a volume of 8.3 L, what would be
the density in (g/mL)?
5. If you had both compound A and B in a beaker of water, which compound
would float? The density of water is approximately 1.00 g/mL. Explain your
answer.
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Part B: Using MSDS to find density and work problems: In this section, you
will need to connect to www.chemfinder.com and log into the site by providing
your username and password.
1. Ethylene glycol is a substance that is commonly used in the automotive
industry as a component of antifreeze. Find the density of ethylene glycol
from chemfinder.com and answer the following questions.
A. The density of ethylene glycol is _________________g/mL.
B. What volume (in mL) of ethylene glycol is needed to have 10.5 g?
Show your work.
C. What is the mass (in g) of ethylene glycol if there is 50.0 mL in a
graduated cylinder? Show your work.
2. Isopropyl alcohol, also known as rubbing alcohol, is used as a disinfectant
and as a solvent. Find the density of isopropyl alcohol using chemfinder.com
and answer the following questions.
A. The density of isopropyl alcohol is __________________g/mL.
B. If you used 25 mL of isopropyl alcohol to clean a CDrom, how many
grams were used? Show your work.
C. A chemical stockroom assistant ordered 12.5 kg of isopropyl alcohol.
How many liters of solution did she order?
3. If water, ethylene glycol and isopropyl alcohol were placed in a beaker, what
would the layers look like? Which is most dense, which is least dense?
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4. Pick any chemical substance that you have interest in from
www.chemfinder.com and provide the following information.
A. What chemical substance did you choose? ______________________
B. What is its density? ________________g/mL
C. If you needed to order 25 L of the substance, what would be its mass
(in kg)? Show your work.
Part C: Everyday chemical densities and density columns: In this section,
you will need to connect to
http://www.scjohnson.com/msds_us_ca/default_en.asp and find two products
you would like to investigate. Indicate the brand and product, report its density
and answer the following questions.
1. The first brand I chose was ____________________ in which the product
was ___________________________.
A. The density for this item is __________________g/mL.
B. If this item was packaged in an 8 ounce container, what would the
mass of the product be? (Note: there are 29.5 mL per 1 U.S. ounce).
2. The second brand I chose was ____________________ in which the product
was ___________________________.
A. The density for this item is __________________g/mL.
B. If you ordered 5 lbs of this product, how many mL would be shipped to
you? (Note: there are 454 g per 1 lb).
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3. Share your one of your two products and densities with your classmates.
Record the products and densities of your classmates in the table below. Do
not record repeat data. Rank the densities from lowest (1) to the highest (16).
Substance
Density (g/mL)
Rank (lowest to highest
density)
4. Create a density column with four products from the table above in the beaker
below. Provide the name of the product and its density.
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Assessment
Sink or Float? Working with Densities
Density Worksheet
Part A: Revisiting Density: When chemists perform separations, looking at the
densities of chemicals are important. Density is expressed in terms of an amount
of mass per unit of volume a substance has, for example g per mL. The formula
for density is D = mass / volume.
Directions: Please read each question carefully. Complete each question by
showing your work and boxing your answer.
1. (2 pts)If you were asked to solve for mass given density and volume, what
would the formula now look like?
2. (2 pts) If you were given mass and density, how would you calculate volume?
3. (3 pts)If compound A had a mass of 5.6 g and a volume of 8.3 mL, what
would be the density in (g/mL)?
4. (3 pts) If compound B had a mass of 9.5 kg and a volume of 8.3 L, what
would be the density in (g/mL)?
5. (3 pts)If you had both compound A and B in a beaker of water, which
compound would float? The density of water is approximately 1.00 g/mL.
Explain your answer.
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Part B: Using MSDS to find density and work problems: In this section, you
will need to connect to www.chemfinder.com (©2004 CambridgeSoft
Corporation) and log into the site by providing your username and password.
1. Ethylene glycol is a substance that is commonly used in the automotive
industry as a component of antifreeze. Find the density of ethylene glycol
from chemfinder.com and answer the following questions.
A. (1 pt) The density of ethylene glycol is _________________g/mL.
B. (3 pts)What volume (in mL) of ethylene glycol is needed to have 10.5
g? Show your work.
C. (3 pts) What is the mass (in g) of ethylene glycol if there is 50.0 mL in a
graduated cylinder? Show your work.
2. Isopropyl alcohol, also known as rubbing alcohol, is used as a disinfectant
and as a solvent. Find the density of isopropyl alcohol using chemfinder.com
and answer the following questions.
A. (1 pt) The density of isopropyl alcohol is __________________g/mL.
B. (3 pts)If you used 25 mL of isopropyl alcohol to clean a CDrom, how
many grams were used? Show your work.
C. (3 pts) A chemical stockroom assistant ordered 12.5 kg of isopropyl
alcohol. How many liters of solution did she order?
3. (3 pts)If water, ethylene glycol and isopropyl alcohol were placed in a beaker,
what would the layers look like? Which is most dense, which is least dense?
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4. Pick any chemical substance that you have interest in from
www.chemfinder.com and provide the following information.
A. (1 pt)What chemical substance did you choose?
______________________
B. (1 pt) What is its density? ________________g/mL
C. (3 pts) If you needed to order 25 L of the substance, what would be its
mass (in kg)? Show your work.
Part C: Everyday chemical densities and density columns: In this section,
you will need to connect to
http://www.scjohnson.com/msds_us_ca/default_en.asp and find two products
you would like to investigate. Indicate the brand and product, report its density
and answer the following questions.
1. (2 pts) The first brand I chose was ____________________ in which the
product was ___________________________.
A. (1 pt)The density for this item is __________________g/mL.
B. (3 pts) If this item was packaged in an 8 ounce container, what would
the mass of the product be? (Note: there are 29.5 mL per 1 U.S.
ounce).
2. (2 pts) The second brand I chose was ____________________ in which the
product was ___________________________.
A. (1 pt) The density for this item is __________________g/mL.
B. (3 pts)If you ordered 5 lbs of this product, how many mL would be
shipped to you? (Note: there are 454 g per 1 lb).
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3. (5 pts) Share your one of your two products and densities with your
classmates. Record the products and densities of your classmates in the
table below. Do not record repeat data. Rank the densities from lowest (1) to
the highest (16).
Substance
Density (g/mL)
Rank (lowest to highest
density)
4. (3 pts)Create a density column with four products from the table above in the
beaker below. Provide the name of the product and its density.
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Links to Course Competencies
This RWLO could be applied in the following courses: fundamentals or
introductory chemistry. Specifically, this RWLO meets the following course
competencies:

Students will have the ability to calculating density.

Students will be able to perform unit conversion.

Students are able to locate densities of chemicals by finding MSDS on the
Internet.

Students have the capacity to determining what layer a substance will be
(i.e. sink or float) by using density.
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Supplementary Resources

For a summary on solving density problems as well as static density
values: http://www.simetric.co.uk/si_liquids.htm © 1998 - 2006 r walker

Another summary for density that contains static density values:
http://hypertextbook.com/physics/matter/density/

Excellent Shockwave Demonstration and an activity that can be given to
students for extra practice
http://ww2.unime.it/weblab/mirror/ExplrSci/dswmedia/density.htm

For visual learners, the following website shares tips on providing a
density demonstration to your class.
http://www.elmhurst.edu/~chm/demos/index.html
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Recommendations
Recommendations for Integration:
This RWLO is recommended for use in the beginning of a fundamentals or
introductory chemistry class in which mass, volume and density are discussed.
Back-up:
In order to deal with any source of Internet problem, schools with chemistry
laboratories should have printed MSDS available for students, teachers, etc. to
look through. The educator can use previously printed MSDS sheets. Another
option is to print out various MSDS from the Internet ahead of time to ensure that
the activity can still be performed.
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