CHM1025C
HandsOn Experiment 3
Density and
Measurement
GOALS:
1.
To measure
liquid volume as accurately as possible with graduated cylinders.
2.
To measure the
volume of irregular shaped solid objects by liquid volume displacement.
3.
To measure
liquid volumes by pipetting into containers.
4.
To weight
objects as accurately as possible on a Top Loader Balance.
5.
To weigh objects
to six significant figures on an analytical balances.
6.
To calculate the
density of known and unknown solids and liquids by measuring the mass and the
volume of the objects with lab instruments.
7.
To observe
experimental deviations through error of instruments or students.
8.
To introduce the
terms accuracy, precision, reliability, sensitivity as related to an analytical
procedure.
EQUIPMENT:
10 ml Graduated cylinder
100 ml Graduated cylinder
10 and 25 ml Volumetric
pipette
25 to 50 ml Erlenmeyer
Flask with solid rubber stopper
110°C Thermometer
CHEMICALS OR UNKNOWNS:
One solid rubber stopper (
either a #2, #1, or #0 as long as it freely fits into
the 100 ml graduated cylinder)
Unknown solid: Metal slugs
in box at the front desk or box of pennies
Distilled water
Unknown liquid: Acetone,
Alcohol, other organic Liquid
INSTRUMENT:
Top Loading Balance (0.01g)
Top Loading Balance (0.001g)
PROCEDURES:
(1) The student should read the experiment before
attending lab.
(2) The student should copy the sample data page into
her/his lab notebook.
(3) Turn in your Measurement experiment’s Post Lab Report
and Data Page copies from your lab notebook
PART A: DENSITY OF A KNOWN SOLID
(1) The students will calculate the density of rubber by
measuring the mass and the volume of the rubber stopper. The rubber stopper
must be small enough so that it will not jam in the graduated cylinder. The
students should use a 100 ml graduated cylinder.
(2) The 100 ml graduated cylinder should have division
marking for each milliliter so that the student may measure the volume
estimated to the nearest 3/10 or 2/10 of a milliliter.

Remember
to always read a graduated cylinder with your line of sight directly
perpendicular to the BOTTOM
of the meniscus. On a
white piece of paper, make a heavy dark line at least ¼ in thick. Place the
paper, behind the graduate. Slide the paper up until the top of the dark line
is about one division below the meniscus. 
This technique will make the meniscus more
prominent and easier to read, allowing you to estimate between the lines for
one more significant figure.
(3) Your graduated cylinder must be clean. Clean
glassware will be free of water droplets clinging above the meniscus. (water
film is okay) Place 15 ml or more water in the graduate. Read the volume
accurately and record in your lab notebook. Your reading should estimate one decimal place.
(4) The student will next weigh the rubber stopper
directly on the Top Loading Balance on your lab island. The mass should be
recorded to the nearest 0.01 gram. Record the mass in your lab notebook.

(5)
Then the student will carefully slide the stopper into a
graduate by tipping the graduate to a 45° angle. The student should not
splash one drop. Tap the graduate to free any trapped air bubbles. If any
water droplets are clinging above the meniscus, you will have to wash the
graduate with soap and water and begin again. (6)
The student will record the new volume in the lab notebook.
Calculate the volume of the stopper,
by subtracting the reading #3 from the reading #6. This is known as a volume of a solid by liquid replacement. 
(7) Using a calculator, divide the mass of the stopper by
its volume to determine the density. DENSITY
is MASS PER UNIT VOLUME. Therefore by dividing the mass of the rubber
stopper by its volume, the density may be calculated.
Since the mass should be at
least two figures accurate and the volume at least two figure accurate the
density should be calculated to three significant figures, the rounded off to
two significant figures answer.
The correct answer is 1.24g/ ml for the
black stoppers and 1.44 g/ ml for
the green stoppers. Rounded off, that would be 1.2 and 1.4
PART B: DENSITY OF AN UNKNOWN SOLID
(1) Calculate the density of an unknown solid assigned to
you by your instructor. Use the procedures similar to PART A, with the following modifications: (metal slugs in the box
on the front desk or 25 Post 1982 pennies, or pellets)
(2) Use a 10 ml/ 25 ml/ or 50 ml graduate that has
division marking at least 2/10 of a ml or preferably 1/10 of a ml(10 mL
graduate), that the object(s) will fit inside.
(3) Weigh the metal slugs or pennies. Record in your lab
notebook.
(4) Measure approximately 5 ml of water in the 10 ml
graduate or 10 ml in 25 ml graduate and read the volume level to the nearest
2/10 or 2/10 of a ml. Some of our
graduates will come close to the nearest 3/10 ml.
(5) Tilt the graduate and carefully slide the unknown
into graduated cylinder, so as not to splash out any water. Make sure the
unknown is completely submerged and the water below the 10 ml line/or top line.
Record the volume.
(6) Calculate the volume of the solid.
(7) Calculate the density of the solid to the nearest 1
/10 of a gram by rounding off the answer.
(8) Using a paper towel from the wash sink, drain off the
water from the graduate, pour the unknown on the towel (careful not to spill).
Fold the towel and blot until dry. Put the dried unknown back on the cart or
front desk.
PART C: DENSITY OF A KNOW LIQUID
(1) With a pipette, small flask, and a Top Load Balance
(0.001g) student will calculate the density of water to three significant
figures.
(2) Weigh you 50 ml stoppered dried flask.
(3) Using your 100 ml graduate, obtain about 40 or 50 ml
of deionized water. (squeeze bottle or from carboy at washup sink)
(4) After you have made your first weighing, pipette 25
ml of deionized water in your weighed flask. At the fill mark on the pipet (line above the bubble) exactly 25.0 ml
water can be measured with a SENSITIVTY of _+ 2/100 of an ml.
(5) 25.00 ml has been listed in your lab notebook.
(6) Weigh the flask and contents on the same Top Loading
Balance you used before. Refer to your procedures or
(7) Calculate the mass of the water. (subtract empty flask
from the flask plus water)
(8) Calculate the density of water to three decimal
places.
(9) Record the temperature of the water by using a 110°C
Thermometer. Use the table on the next page for the correct density.
TABLE FOR
DENSITY OF WATER
TEMPERATURE °C 
DENSITY g/ml 
TEMPERATURE °C 
DENSITY g/ml 
15° 
0.9979 
26° 
0.9959 
16° 
0.9978 
27° 
0.9957 
17° 
0.9977 
28° 
0.9955 
18° 
0.9975 
29° 
0.9952 
19° 
0.9973 
30° 
0.9949 
20° 
0.9972 
31° 
0.9946 
21° 
0.9970 
32° 
0.9944 
22° 
0.9968 
33° 
0.9941 
23° 
0.9966 
34° 
0.9938 
24° 
0.9964 
35° 
0.9935 
25° 
0.9962 
36° 
0.9932 
PART D: DENSITY OF UNKNOWN LIQUID
(1) Using the Top Load Balance, (0.001 g) and a 10 ml
pipet, dry flask, calculate the density of an unknown liquid. Use the same
procedures as you followed in PART C, but add these modifications.
(2) Using a clean dried 25 ml stoppered flask, weigh on
the Top Loading Balance (0.001 g).
(3) Obtain an unknown from the front desk (Acetone, Ethyl
alcohol (ethanol), or methyl alcohol (methanol) in a small beaker. Pipette,
using a 10.00 ml volumetric pipette, 10.00 ml into the weighed flask stopper.
(4) Weigh the stoppered flask on the Top Loader Balance
(0.001 g).
(5) Calculate the density of the unknown. Have your data
page in your lab notebook initialed by the instructor before leaving the lab.