EXPERIMENT 1
MEASUREMENTS: VOLUMES & DENSITIES
Introduction: Volume can be measured directly with a volumetric device such as a graduated
cylinder or calculated from dimensions if one has a regular geometric shape such as a cylinder or
rectangular bar. Density is found by dividing mass by volume. In this experiment, the densities
of water, wood and a metal are determined.
Materials
two test tubes of different size (check one out from the stockroom if needed)
50 mL graduated cylinder
a wooden block (obtain from instructor)
ruler
metal bar or cylinder (obtained from instructor )
Procedures.
1. Determining the volumes of test tubes by two methods.
a) Use the cm ruler to measure inside diameters
and lengths of two different test tubes to the
appropriate degree of precision. (When measuring
the height (h) of the inside of the tube, measure to
where you think the curvature begins near the bottom
of the tube.) If all your test tubes are the same,
borrow one of a different size.
Do not include the thickness of the glass in the reading.
Now calculate the volume of each test tube using the formula V = r2h (  = 3.14, r = the radius
= ½ the diameter. Round off your calculation to the appropriate number of significant figures.
b) Measure the volumes of the two test tubes used in part 1a, by filling them with water and
pouring the water into a 50 mL graduated cylinder. Read the volume on the cylinder by
estimating to the nearest 0.1 mL
2. Measurements on a wooden block.
Measure the length, height, and width of a wooden block. Calculate the volume (in cm3) from
the three dimensions (length x width x height) to the appropriate number of significant figures.
Weigh this same wooden block, to the nearest 0.01 g (2 decimal places). Now you can calculate
the density of the wood, in g / cm3
3. Measurements of a metal bar or cylinder.
Obtain a metal bar or cylinder from the instructor. Record its code #. Determine the density of
the metal object using the same procedure as in part 2. Using the densities given on page 6,
determine which metal you have (your choices are Al, Fe, Ni, Zn, Pb, Sn, Cu, Ag, Au, Pt, and
Hg). Your instructor may confirm the identity of your metal. Determine the percent error in
your density.
4. Measurements on water
Weigh a clean dry 50-mL graduated cylinder to 2 decimal places Pour water into the cylinder
about ½ full. Read the volume in the cylinder to the nearest 0.1 mL Now weigh the cylinder
with the water. Don’t spill water on the pan! Calculate the grams of water in the cylinder and
the density of the water. Be sure to include the units.
use the same balance for all your weighings
Look up the accepted value for the density of water at a room temperature of 20oC. (You can
check the CRC Handbook for the value at 20oC; this is close enough to the actual room
temperature in an air-conditioned environment.) Report the value to three significant figures.
Calculate the % error in your value for the density of water. The general formula for calculating
a percent error is:
% error =
[ experimental value – accepted value ] x 100
accepted value
Keep the + or – sign in the answer. It indicates whether your result is high or low.
EXPERIMENT 1: Report Sheet
Name: __________________________
MEASUREMENTS: VOLUMES & DENSITIES
Section __________
Part 1a: Data using the ruler (show units)
Calculated values
diameter (d)
height (h)
volume ( cm3 )
1.
_________
________
___________
2.
_________
________
___________
test tube #
Show the set-up of one volume calculation.
Part 1b: Data using the graduated cylinder (show units)
test tube #1 :
volume __________
test tube # 2:
volume: ___________
Part 2: Data: wood block
height _______ length _______ width _______
mass: ________
Show set-ups for volume and density calculations in part 2.
Calculated values: (show units)
Volume: _____________
Density ____________
Part 3: Data: metal bar or cylinder
Calculated values
dimensions: _________________________
(Specify)
___________________________
volume : ______________
density : ______________
___________________________
mass:
__________________________
identity of metal: _________
density
from table: ____________
Show set-up of volume and density
calculations
% error: _______________
Show set-up of % error calculation
Part 4: Data: water.
mass of cylinder ________________
mass of cylinder
with water:
________________
Calculated values
mass of water: ___________________
density of water: _________________
( from your mass and volume)
volume of water: ________________
density of water from table ________
% error in density: ________________
Show setup of calculations of density and % error
Questions
1. An empty graduated cylinder weighs 79.35 g.
It was filled to the extent shown in this partial segment
of a graduated cylinder with a liquid called carbon
tetrachloride (CCl4). The density of CCl4 is 1.61 g/mL
How many grams does the cylinder weigh together with
the CCl4?
2.
35
25
Compare the volumes of the test tubes obtained in part 1a and 1b in this experiment.
Which method, the measurement of dimensions, or the measurements of volume
with a graduated cylinder, do you think gives a better result? Explain why.
(recall the assumption about measuring the test tube as a cylindrical object).
3a) Look at the densities of the elements on the periodic chart on page 6.
What general trend, an increase or decrease in density, do you see as you look from the
top to bottom in a given group (vertical column of elements, for example Li to Fr)?
b) What general trend do you see in the densities of elements on the left half of the
periodic table, as you read from left to right (for example from K to Cr ?
4a) What is the densest element?
_________
(refer to the table on page 6)
b) If you have a coin made of this element that weighs 100.0 g, and has a thickness of
4.00 mm, what would the diameter of the coin be, in cm ? ( V = r2h h = 4.00 mm)
5. 12 karat gold contains 50% gold and 50% copper. What do you think the density
of 12 K gold should be (Hint, look up the densities of pure copper and pure gold.)
OPTIONAL CHALLENGE PROBLEM: Compare the densities of the following gases:
nitrogen, oxygen, fluorine gaseous state (N2, O2, F2). Is there a trend? What units are used to
express densities of gases? What happens with Ne? Does it follow the trend? Try to explain
why/why not?