Student Activity – Rock-n-Roll
Rock-n-Roll
Investigating the Weathering of Rocks
Weathering is the break-up or decomposition of rock resulting from exposure to Earth’s atmosphere. Weathering occurs due to either mechanical or chemical processes. Mechanical
weathering takes place when rocks are broken apart by physical activities such as ice wedging or
the biological actions of plants and animals. Chemical weathering is generally caused by
hydrolysis, oxidation, or dissolving-chemical reactions that alter and break down rocks.
In this activity, you will conduct two separate weathering experiments. Part I will model
mechanical weathering using limestone gravel. Part II will model chemical weathering of the
same material under both warm and cold conditions.
Erosion plays an important role in the weathering process. By transporting weathered material
away, erosion exposes new surface area to weathering agents. In these experiments, the erosion
process will be modeled in the rinsing procedures. In Part I, using a plastic screen while rinsing
establishes a protocol for what size material would be eroded away in your model.
Purpose
In this activity, you will examine and compare the physical and chemical weathering of
limestone and granite rocks.
Materials
200 mL granite chips (small rocks)
200 mL limestone or marble chips (small rocks)
balance
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1–2 canisters, plastic
sieve, small mesh
4 beakers, 250 mL
50 mL vinegar
50 mL water
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Student Activity – Rock-n-Roll
Procedure
Part I: Physical Weathering
1. Predict whether limestone or granite will show the greatest change in mass after being shaken
for 5 minutes. Write your hypothesis on the student answer page.
2. Using a 250 mL beaker, add limestone gravel to about the 200 mL mark.
3. Rinse the gravel with water and drain while covering the top of the beaker with a plastic
screen. Use a paper towel to absorb excess moisture.
4. Measure the mass of an empty plastic bottle (without the cap) using the balance. Record the
results on the student answer page.
5. Add the rinsed gravel to the plastic bottle. Re-measure the mass of the bottle (without the
cap) with gravel and record this value on the student answer page. Subtract the mass of the
empty bottle from the total mass of the bottle and gravel to obtain the mass of the gravel.
Record this mass in the appropriate space on the student answer page.
6. Cap the bottle and shake vigorously with a consistent rhythm for 5 minutes.
7. Rinse the gravel in the plastic bottle again. Make sure to rinse any material that is stuck to the
cap back into the bottle. Again, use the screen to sort which material will be rinsed away.
8. Re-measure the mass of the bottle (without the cap) with gravel after the rinse and record this
value on the student answer page.
9. Empty, rinse, and dry the bottle. Re-measure the mass of the bottle (without the cap) to
determine whether there has been any change in mass for the bottle. Calculate the final mass
of the gravel and record this value.
10. Subtract the final gravel mass from the initial gravel mass and record this value on the
student answer page. This value is the mass of the material weathered away in this
experiment.
11. Repeat Steps 1–10 using granite gravel.
Part II: Chemical Weathering
1. In this part of the experiment, you will be using weak vinegar to weather rocks. You will also
be using varying temperatures to see if temperature acts as a catalyst. Predict which of the
four beakers containing limestone (or marble) chips—warm vinegar, cold vinegar, warm
water, cold water—will show the most change in mass. Write your hypothesis on the student
answer page.
2. Obtain four clean, dry beakers. Label one beaker “Cold Vinegar,” one beaker “Cold Control,” one beaker “Warm Vinegar,” and the last “Warm Control.”
3. Measure the mass of each beaker and record the values for each on the student answer page.
4. Fill each beaker up to the 50-mL mark with rinsed and dried limestone (or marble) gravel.
5. Measure the mass of each beaker with gravel and record the values on the student answer
page in the space provided for each sample.
®
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Student Activity – Rock-n-Roll
Procedure (continued)
6. Fill the “Cold Vinegar” beaker with enough cold vinegar to completely cover the gravel.
Repeat this step for the “Warm Vinegar” beaker using warm vinegar.
7. Fill the “Cold Control” beaker with enough cold water to completely cover the gravel.
Repeat this step for the “Warm Control” beaker using warm water.
8. Allow each sample to react for 20 minutes. Gently swirl each beaker once every minute.
9. While the experiment progresses, observe and record any differences you notice in the
contents of the beakers.
10. Rinse and dry each sample using the sieve. Take care not to lose any gravel.
11. Measure and record the final mass of the beaker with gravel for each sample on the student
answer page.
12. Subtract the final mass from the initial mass for each sample. Record this value on the
student answer page.
Hypothesis
Part I: Physical Weathering
Part II: Chemical Weathering
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Student Activity – Rock-n-Roll
Data and Observations
Table 1: Physical Weathering
Item
Initial Mass (g)
Final Mass (g)
Change in Mass (g)
bottle
bottle and limestone gravel
limestone gravel
mi =
mf =
m=
mi =
mf =
m=
bottle
bottle and granite gravel
granite gravel
Observations: Physical Weathering
Table 2: Chemical Weathering
Sample
Mass of
Beaker (g)
Initial Mass of
Final Mass of
Mass of
Change in
Beaker and
Beaker and
Gravel, mi (g)
Mass, ∆m (g)
Gravel (g)
Gravel (g)
Cold Vinegar
Warm Vinegar
Cold Control
Warm Control
Observations: Chemical Weathering
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Student Activity – Rock-n-Roll
Analysis
Part I: Physical Weathering
1. What factors do you think will affect the rate of weathering in your model?
2. What procedures could your group implement to ensure a consistent rate of weathering?
3. How could you change the experiment to test for these variables?
4. Using the following formula, determine the percent change of material in the weathering
model presented:
%
m
mi
100
where ∆m = change in mass and mi = initial mass. Show your work.
Part II: Chemical Weathering
1. Using the following formula, determine the percent change of material in the weathering
model presented:
%
m
mi
100
where ∆m = change in mass and mi = initial mass. Show your work
®
Copyright © 2011 Laying the Foundation , Inc., Dallas, Texas. All rights reserved. Visit us online at www.ltftraining.org.
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Student Activity – Rock-n-Roll
Conclusion Questions
1. Based on your calculations, which model (chemical or physical) had the greatest rate of
weathering?
2. Based on your observations, what factors affect rates of weathering?
3. Describe the difference between mechanical and chemical weathering.
®
Copyright © 2011 Laying the Foundation , Inc., Dallas, Texas. All rights reserved. Visit us online at www.ltftraining.org.
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