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Name: ____________________
Date: ________ Period: ______
Porosity, Permeability, and Capillarity Lab
(47 points total)
The pore space, or porosity, of a rock or sediment is the amount of the material that
contains open spaces. The permeability is the rate at which water or other fluids will pass
through theses open spaces. Capillarity is the rate at which water is pulled upward from
the water table into pore spaces by capillary action. In general, particles with larger pore
spaces have better permeability and poorer capillarity.
Materials List:
 Coarse sand, medium sand, fine sand, & a mixture of all three sands.
 2-100mL clear graduated cylinders.
 Watch with second hand.
 2-400mL beakers.
 Masking tape, scissors, marking pencil, metric ruler.
 Paper towels.
 Glass tube, 1cm x 15cm.
 Ring stand & test tube clamp.
Procedure:
Part A. Porosity and Permeability.
1.
Use one of the beakers to obtain a sample of one of the four sand samples.
2. Fold a piece of filter paper in half and then fold it in half again so it forms a cone. With
scissors, cut off the pointed end and open the paper so that it forms a funnel. Use it to
fill one of the graduated cylinders to the 50-mL mark.
3. Fill the other graduated cylinder to the 50-mL level with water.
4. Read all of this procedure in steps 4 and 5 before starting. The 50-mL of water is
to be poured gently but quickly into the cylinder containing the sand. The time needed
for the water to reach the bottom of the cylinder is to be timed by another student.
5. Determine the time between the instant the water is poured into the cylinder and the
instant the first drop reaches the bottom of the cylinder. This time indicates the
permeability of the sample. Record the time on the data chart.
6. When the water has completely wet all the particles in the cylinder, tap the cylinder
gently to remove any remaining air bubbles between the particles.
7. Read the level of the water in the cylinder to the nearest 10 th of a millimeter. When
you added water to the cylinder, any pore space in the sediment was replaced by water.
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The water level is the volume of dry sediment plus the sediment alone (no pore space).
Record this volume on the data chart.
8. To obtain a value for the porosity of the sample, first subtract the volume of the water
plus sediment from the original volume of dry sediment plus pore space plus water (100mL). This gives you the volume of the pore space. Record this volume on the data chart.
9. To determine the percent porosity of the original dry sample, divide the volume of the
pore space by the volume of dry sediment plus pore space (50-mL) and multiply by 100.
Record the porosity in the data chart.
10. Place the used, wet sample in the container supplied by your teacher for particles of
that size. Wash out the cylinder and dry it thoroughly with a paper towel.
(20 points total)
Data Chart
Coarse
Sand
Time for water to reach bottom of
cylinder
Part
A
Volume of water +
sediment (mL)
Volume of pore spaces (mL) = 100mL
– (Volume of water + sediment)
Porosity = Volume of pore spaces /
50mL x 100
Part
B
Time for water to rise to 4cm level
Medium
Sand
Fine Sand
Mixed
Sand
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Part B. Capillarity.
1.
Fill the second beaker with water.
2. Obtain a hollow glass tube. Using a metric ruler and a marking pencil, draw a line
completely around the tube 4cm from one end.
3. Using the same end of the tube as a guide, trace the circular outline on a piece of filter
paper. Then draw a freehand circle around the first circle, but about 1 cm larger all the
way around. With scissors, cut out the larger circle.
4. Tape the filter paper to the end of the tube on which you drew the 4 cm line, sealing off
the open end completely. Be careful not to cover any part of the 4 cm line with filter
paper or tape.
5. Holding your hand over the end with the filter paper, fill the tube to about a depth of
about 10 cm with one of the four sand samples.
6. Clamp the tube to a ring stand. Place the beaker of water on the base of the ring stand
below the tube.
7. Read all of this procedure before starting. You will place the end of the tube with
the filter paper just below the surface of the water in the beaker. Determine the
elapsed time between the instant that the tube is placed in the water and the instant
that the first drop reaches the 4 cm line. This time is an indication of the capillarity of
the particles. Record this value on the data chart.
8. Hold your tube above the container designated by your teacher for particles of this size
and remove the filter paper and tape. Pour the wet sample into the container. Wash
and dry the glass tube.
9. Have four groups who recorded data for the different particle sizes write their data
for parts A & B on the chalkboard. Record this information on the data chart.
Analysis and Conclusion:
(27 points total)
Answer the following questions in complete sentences (RAP: Restate, Answer, & Prove).
1.
The two graduated cylinders each held 50-mL of water and 50-mL of sediment. When
added together why was the final volume of sediment and water NOT equal to 100-mL?
Where did the water go?
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2. For which sample was the water level in the graduated cylinder (volume of water plus
sediment) the highest? Explain why.
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3. How is the difference between the final volume and the initial 100-mL volume related to
the porosity of each sample?
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4. Which sand size (coarse, medium, or fine) has the greatest permeability? What is the
evidence for this answer?
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5. Why does the mixture of sand have the poorest permeability?
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6. Once a sample is wet, a film called capillary water surrounds each particle. What
effects would capillary water have on the permeability of a sample? Why?
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7. Look at your values for the porosity of the coarse, medium, & fine sands. What is the
average of your three values? (The average equals the sum of the three porosity values
divided by three). Are all three values within 10% of this average? If differences
within 10% are ignored, how do your values for the porosity of these three samples
compare?
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8. Which particle size has the best capillarity? What is the evidence for your answer?
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9. Which should be more permeable, sandstone or shale (mudstone)? Why? Which should
have better capillarity? Why?
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