Viscosity, Thixotropy and Dilatancy of Petroleum-Based Materials
Elementary School Experiments & Background information
For Science Labs, Lesson Plans, Class Activities & Science Fair Projects

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## Viscosity of Some Petroleum-based Materials

Developers:

Pamela G. Ponce
East Goshen Elementary
West Chester Schools
West Chester, PA

Dr. Robert J. Smith
Polymer Process Research
Rohm and Haas Company
Spring House, PA

Level:

Fifth

Discipline:

Physical Science

Goals:

To have students investigate the properties of flow and viscosity.

Specific Objectives:

To strengthen observational skills. To record observations in a science journal. To strengthen the connection between math and science. To work cooperatively and communicate findings.

Background:

Viscosity is one of a group of properties of fluids called transport properties, which are related to the flow of matter or energy. A material with a high viscosity flows slowly and with difficulty, like honey. A material with a low viscosity flows readily, like water. You will determine relative viscosities, which means ranking materials on a range from the most to the least viscous.

The viscosity of a liquid is an important design parameter in numerous practical applications. The pipe dimensions and size and number of pumping stations on the Alaskan pipeline are determined to a large extent by the viscosity of crude oil. The oil is heated to reduce the viscosity. The viscosity of blood affects the throughput in artificial heart-lung machines. When honey is packaged in a plastic dispenser bottle, its high viscosity requires an increase in pressure, by squeezing, to force the honey through the small nozzle.

Materials:

(for each group)

• water
• mineral oil
• kerosene motor oil
• household lubricating oil
• 5 test tubes
• 5 tube caps

Procedure:

Copy this data table in your science journal:

Data Table -- Viscosity Measurements

 Material carbon atoms per molecule average time for bead to fall (s) relative viscosity water -- mineral oil 12-20 kerosene 12-16 motor oil 15-18 household lubricating oil 14-18

1. Determine the average time for a bead to fall from top to bottom within the capped tube containing water. Follow this procedure:
a. Hold the capped tube upright until the ball 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. Determine the number of seconds required 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 this procedure for each petroleum-based sample.
3. Rank your samples in order of relative viscosity, assigning the number 1 to the least viscous material (the one in which the ball fell fastest).

Discussion Questions:

1. Propose a rule based on observations made in this activity regarding the relative number of carbon atoms per molecule and the resulting viscosity of the material.
2. Petroleum refiners and distributors must consider the viscosity of their products when shipping diesel/fuels and motor oils to different parts of the country. Explain why the diesel/fuel shipped to a northern state (say Alaska) in winter must be different from that shipped to southern state (say Florida) in summer. How would you adjust the products

Extensions:

1. Use different sizes of test tubes.
2. Graph results
3. Find out: Is viscosity a major factor both in oil spills and oil fires? How does it effect treatment and/or outcome?
4. Have each group design their own experiment to share with other groups.

References:

Chem Com: Chemistry in the Community, ACS Kendall/Hunt Publishing Co. Iowa 1988.

 This experiment is courtesy of