# u3b3viscosity density

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```					B.3 LABORATORY ACTIVITY: VISCOSITY AND DENSITY
Viscosity is the term for resistance to flow. A material with high viscosity,
like honey, flows slowly and with difficulty. A material like water, with a low viscosity, flows readily. In this
activity you will determine relative viscosities, which means comparing the viscosity of a substance with that
of other substances. Then you can rank the substances comparatively, from the most viscous to the least. You
will measure the densities and relative viscosities of several petroleum-based materials, and for comparison,
the same properties for water. To determine densities, you will measure the masses and volumes of liquid
and solid samples.

PROCEDURE
Sample Examination
1. Obtain the materials listed in your sample examination table.

2. Record the state (solid or liquid) of each sample.

3. Which material would you expect to have
a. the lowest boiling point?

b. the highest boiling point?

Data Table 1                         Sample Examination
Material                   Carbon Atoms per Molecule             State at Room
Temperature (s,l,g)
Water                                                 0
Vegetable Oil                                      10 - 15
Mineral Oil                                        12 - 20
Motor Oil                                          15 - 18
Paraffin Wax                                        >19
Asphalt                                             >34

DENSITY MEASUREMENTS:
LIQUID SAMPLES
1. Your teacher will give you average values for the mass of an empty capped tube, the mass of a bead, and
the volume of liquid in a sample tube. For convenience, record these values at the top of your Density
Measurements data table.

2. Weigh each capped tube containing a petroleum product sample. Also weigh a capped tube containing
water. Record the masses.

SOLID SAMPLES
3. Fill a 25-mL graduated cylinder with water to the 10mL mark.

4. Weigh each solid sample carefully. Record the masses.

5. Carefully drop the first weighed solid sample into the water in the cylinder. Measure the increase in
volume. Record this value.

6. Repeat Step 5 for the other solid sample.
B.3 LABORATORY ACTIVITY: VISCOSITY AND DENSITY
Name : _________________________________
DENSITY CALCULATIONS:
LIQUID SAMPLES
1. Calculate and record the mass (in grams) of each liquid sample, using masses obtained in Steps 1 and 2 for
the total mass, the capped tube, and the bead. Use this formula:

Sample mass =          total mass - (capped tube mass + bead mass)

2. Using your calculated sample masses and the volume of liquid in each capped tube, calculate the density
of each sample (in grams per milliliter). Record these values. For example, suppose the sample mass is
40.2 g and the volume is 36.7 mL.

Sample density =       sample mass             = 40.2 g        =        1.10g/mL
average volume            36.7 mL

SOLID SAMPLES
3. Using the sample masses and increases in water volume found in Step 5, calculate the solid sample
densities (in grams per milliliter). The calculation is the same as the one illustrated for liquids in Step 2 of
the last calculation except for using the volume without the bead.

Data Table 2                              Density Measurements

Mass of capped tube:_______

Volume in Tube with Bead: _______             Volume in Tube without Bead: _______

Liquid with Bead           Mass of Capped Tube,           Calculated Mass of           Calculated Density of
Bead, and Liquid (g)               Liquid (g)                 Material (g/mL)

Water

Vegetable Oil

Mineral Oil

Motor Oil

Solid without Bead          Mass of Capped Tube,           Calculated Mass of           Calculated Density of
and Solid (g)                   Solid (g)                 Material (g/mL)

Paraffin Wax

Asphalt
Name : _________________________________

Apparatus for determining relative viscosity.

RELATIVE VISCOSITY
1. Determine the time needed for the bead to fall from top to bottom within the capped tube containing water.
a. Hold the capped tube upright until the bead is at the bottom.

b. Gently turn the tube horizontally. (The bead will stay at one end.)

c. Quickly turn the tube upright so the bead is at the top.

d. Record the number of seconds needed for the bead to fall to the bottom of the tube.

e. Repeat this procedure three more times. Calculate the average time required for the bead to fall.

2. Repeat Step 1 for each liquid petroleum-based sample.

3. Rank your samples in order of relative viscosity, assuming number 1 to the least viscous material (the one
through which the bead fell fastest).

4. Wash your hands thoroughly before leaving the laboratory.

Data Table                                 Viscosity Table
Material                   Average Time for Bead to Fall (s)                Relative Viscosity (1-4)
Water
Vegetable Oil
Mineral Oil
Motor Oil

QUESTIONS
1. The density of oil plays a major role in oceanic oil spills and in fires. Explain.

2. Propose a generalization, based on your observations in this activity, about the connection between the
number of carbon atoms in a molecule and a substance's viscosity.

3. Suppose a classmate suggests that petroleum fractions can be separated at room temperature on the basis
of their viscosities.