Chemistry Worksheet Date __________________ Period __ Name _____________________________
Density Activities Lab Report
CW density activity report ver5 012212.doc
.
Density is the ratio of the mass of an object to the volume of the object. D = m/V. Mass is a measure of the
quantity of matter, and is usually measured in grams. Volume is a measure of the space something takes up, and is
usually measured in mL or cubic centimeters. 1 mL = 1 cm2. 1000 mL = 1L. The units of density are usually
g/cm3 for solids, g/mL for liquids and g/L for gases.
Instructions: Follow the guidelines below as you measure the densities of various objects and substances. Use
your laboratory notebook to record all of the data and do the calculations. Copy the data and results to these
pages to turn as your lab report. Use the following equation to computer percent error.
Percent error =
accepted value − exp erimental value
×100
accepted value
1. Measure the mass a metal cylinder. Measure the height and diameter of the metal cylinder and compute the
volume using the equation V = πr2h. You can identify the metal cylinder by the chemical symbol on one end.
Compute the density of the metal, look up the accepted value for the density and compute the percent error.
Identity of metal cylinder: ____________________
Mass __________________________________________
Diam. and height in cm_______________________
Volume in cm3___________________________________
Experimental density ________________ Accepted density ________________ % error ___________________
2. Repeat the experiment, but determine the volume of the metal cylinder using liquid displacement.
Initial volume of water _______________________
Final volume of water _________________________
Volume of cylinder __________________________
Experimental density __________________________
R
3. Determine the densities of cork stoppers and rubber stoppers
by using the formula for a “conic frustum” given at the right.
height, h
V=
(
πh 2
R + Rr + r 2
3
)
r
Mass of cork stopper ________________________
Mass of rubber stopper ___________________________
Large diameter _____________________________
Large diameter _________________________________
Small diameter _____________________________
Small diameter _________________________________
Height ____________________________________
Height ________________________________________
Volume ___________________________________
Volume _______________________________________
Experimental density ________________________
Experimental density ____________________________
Accepted density of cork _____________________
Accepted density of rubber ________________________
Percent error ______________________________
Percent error ___________________________________
Place the cork and rubber stoppers in water and see if they float or sink. Write your observations, and the
reasons why below.
4. Consider the case where the cork stopper and the rubber stopper are joined together into a single unit.
Calculate the density of the combination of the two stoppers. Will the combination of the two stoppers float or
sink? Test your prediction and give the results.
5. Density of an unknown liquid. Measure the masses and volumes of a different amounts of the liquid and use a
graph to determine the density. Use the 10 mL graduated cylinder. Mass the cylinder, then add small amounts
of the liquid and measure the mass. Repeat until you eight data pairs. Then graph and determine the slope.
The slope is the density of the liquid.
Data table for organic liquid
mass
volume
mass
volume
6. Identify the unknown liquid: _______________________________
Density of liquid ________________________________________
Percent error ___________________________________________
7. Determine the thickness of a sheet of aluminum foil without altering the foil in any way.
Dimensions of the aluminum foil ________________________________ Area ________________________
Mass of foil _________________________ Look up the density of aluminum _________________________
Thickness of foil in centimeters _________________________ in millimeters _________________________
Show calculations below:
Chemistry Worksheet Date __________________ Period __ Name _____________________________
Density Activities Lab Report
CW density activity report ver5 012212.doc
.
Part Two - Postlab Discussion Questions. Be prepared to offer an answer and defense for each of the following.
Answer on notebook paper.
1. Find the density of water at 20C and round the value to two decimal places.
2. Look at the graph of density vs
temperature. At what
temperature does water have
its maximum density?
0.9998
Density of water (g/cc)
3. It can’t be a coincidence that
the density of water is
essentially 1g/cm3. The metric
system started by defining a
meter and then by defining a
kilogram in terms of a cubic
meter of pure water. What is
the mass in kilograms of a
cubic meter of water?
1.0002
1.0000
0.9996
0.9994
0.9992
0.9990
0.9988
0.9986
0.9984
0.9982
0.9980
0
4. Why does the density decrease
as the temperature increases?
2
4
6
8
10
12
14
16
18
20
Tem perature (C)
5. It is said that water expands about 1/11th of its volume when it freezes. What will be the approximate volume
of one gram of ice at 0C? What will be the density of ice at 0C?
6. When determining the volume of a solid, which method (direct measurements and volume calculation or liquid
displacement) is better? Explain your reasoning.
7. What are some drawbacks when using liquid displacement to determine the volume of a substance
8. What conclusion can you draw concerning the stoppers that float or sink and their densities?
9. How did you determine the combined density of the two stoppers which were connected into a single unit?
10. How is it possible for a battleship, which is made of steel, which is much more dense than water, to float?
11. How is possible for the slope of the line of a graph of mass vs volume to be the density of the liquid?
12. Why is the graphical method for finding density superior to making one measurement of mass and volume or
even several and averaging the densities?
13. In what ways does a variation in temperature affect the density of a substance? Explain. Which would be
affected the most and the least by variations in temperature, solids, liquids or gases? Explain.
14. It is observed that a 12 oz. aluminum can of regular
CocaCola will sink in water, but a 12 oz. aluminum
can of diet Coke will float. Explain.
Nutrition info from the cans of classic
coke (above) and diet coke (right). A
12 ounce can holds 355 mL of liquid.
15. Determine the covalent radius of an aluminum atom using www.ptable.com, and then, assuming that
aluminum atoms are spherical and are arranged edge to edge in a straight line across the thickness of the
aluminum foil, use your results to determine how many aluminum atoms thick the aluminum foil is. (Hint:
Remember the difference between radius and diameter.)
Useful information:
The radii of atoms are given in picometers (pm). Picometers are extremely small, as you might expect. A
picometer is one trillionth of a meter. There are 1 x 1012 pm in a meter, or a picometer is 1 x 10-12 m
1 m = 100 cm
1 m = 1000 mm
1 cm = 10 mm
1 m = 1 x 1012 pm
16. Consider a glass which contains liquid tap water and ice cubes made from tap water in which the water is level
with the top of the glass. When the ice cubes melt, the water does not overflow the glass. Yet we are
concerned about sea-level rise when icebergs, which are made of sea ice or glacial ice, melt in the ocean.
When that occurs the sea level rises. Explain these seemingly contradictory observations. Note: Sea water has
a density of about 1.03 g/mL.
Tap water ice floating in simulated sea water.
Tap water ice has melted, elevating the water
level, contrary to what would happen if the ice
was floating in tap water.
Should we be concerned about the small rise in sea level due to melting sea ice? You may not know that sea
ice contains no salt just like glacial ice. Melting ice decreases the salinity of the ocean water and makes it less
dense, potentially interrupting the "ocean conveyor belt". Check out the "Discussion of sea ice" on the
Introduction to Chemistry page on wikispaces.
Chemistry Lab
Date _________________________ Period __ Name ___________________________
Sample Density Calculations
1. Find the density of an object with a mass of 238. grams and a volume of 59.5 cm3.
2. Find the volume of 9.63 grams of chlorine gas at STP.
3. What is the mass of copper that has a volume of 150.0 cubic centimeters?
4. Determine the mass of a copper sphere with a diameter of 2.00 cm.
5. A cube of zinc has a mass of 400 grams. What is the length of an edge?
6. An unknown metal has a volume of 200. cm3 and a mass of 900. grams. What is the identity of the
metal?
7. An alloy of zinc and nickel has a density of 7.80 g/cm3. What is the percentage of zinc in the alloy?
(Answer this problem on the back of this sheet.)