Mass, Volume and Density
UNIT 2
Objectives
1.
To determine the mass and volume of several samples of matter using a balance that measures
to the 0.01g and the method by water displacement.
2.
To determine whether there is a constant relationship between the mass and the volume of the
samples of a substance.
3.
To calculate the density of a solid object from its mass and volume.
Procedure
1.
Create a data table to hold the following information about two unknown metal solids: Mass in
0.01 grams, initial volume of water, volume of water with metal, volume of metal, and density
of metal. Label this table “Table 1: Individual Data and Calculations”.
2.
Create a second table. Label it “Table 2: Class Data; Mass and Volume of Metal Shapes”.
Have space for up to 12 lab groups’ information for mass and volume for two (2) unknown
metal solids.
3.
Obtain two different unknown metals. Be sure that the samples are clean and dry, and that you
can distinguish between them. Find the mass of each sample on the electronic balance to the
nearest 0.01-gram. Record the mass of each sample on a data table.
4.
Find the volume of each metal sample in the following way. Fill a 25-mL graduated cylinder
about half full with tap water. Record the initial volume of water in the graduated cylinder.
Tilt the cylinder and slide one of the metal samples carefully in the water, so that it doesn’t
break the cylinder or water doesn’t splash out. IT IS IMPORTANT THAT THE SAMPLE IS
COMPLETELY DRY BEFORE IT IS IMMERSED IN WATER; OTHERWISE ERROR
WILL BE INTRODUCED INTO THE VOLUME MEASUREMENT.
5.
Repeat step 4 using the other metal sample. Dry both samples and return them.
Data and Analysis
1.
Calculate the volume of each metal sample by subtracting the initial volume of water in the
cylinder from the final volume. Record the results in your data table.
2.
Calculate the density of each of your samples. Remember that density is the ratio of mass to
volume. Record your results in your data table.
3.
Complete Table 2 by recording the mass and volume data collected by other students in your
class.
4.
Using the class data, plot a graph relating mass and volume. Plot mass (in grams) on the
vertical axis, volume (in milliliters) on the horizontal axis. Choose a scale that will generate a
graph that fits comfortably on a three-quarter page of graph paper. Give your graph a title.
5.
Plot your data on the graph. Use a ruler to draw a best-fit line through each group of plotted
points. You should have two lines (please use two different colors), one for each metal. Note
that not all of the points in a group will lie on the best-fit line through that group of points.
6.
Determine the slope of the line. Remember that if a line goes through a point (0,0) its slope is
y/x. In the graph that you plotted, y/x is equal to mass/volume, which is the formula for
density. Thus, the slopes of the lines you have drawn represent the densities of the metals you
have examined. Show your work of how you calculated the densities of each of the metals
from the slope of the line drawn for that metal
Questions
1.
What does this experiment demonstrate about the density of a substance? What does it
demonstrate about the densities of different substances?
2.
Calculate the percent error for the densities you calculated for your two samples. Your teacher
will provide you with an accepted value for the density of each sample.
Percent error = accepted value – experimental value  100 percent
accepted value
3.
Calculate the percent error in the densities you obtained from the slopes of the lines in your
graph.
4.
Which of the approaches used here is more reliable and accurate: calculating the density from
mass and volume measurements for a single sample, or calculating the density by determining
the slope of the graph of mass and volume data for a number of samples?
5.
Do you think density could be used to identify a substance? Explain your answer. Attempt to
identify the materials used in this experiment by referring to density tables.