Mechanical vs. Chemical Weathering Lab
Purpose:
The purpose of this experiment is to identify the differences between mechanical and chemical
weathering.
Introduction: (paragraph)
- Topic sentence
- What is weathering?
- What is mechanical weathering and what are some causes for it?
- What is chemical weathering and what are some causes for it?
Hypothesis:
Predict whether chemical or mechanical weathering will have a greater effect on the mass of
your rock and give a reason for your prediction.
Materials:
 2 samples each of granite, limestone, sandstone, & marble
 Hydrochloric acid
 Plastic container w/ lid
 2 interlocking metal cans
 Triple-beam balance
 Stopwatch
Procedure:
Independent variable:
Dependent variable:
1. Zero the triple-beam balance.
2. Measure the mass of the rock samples and record it on the data chart.
3. Measure 70mL of Hydrochloric acid in a graduated cylinder then pour it into the plastic
container.
4. Mechanical Weathering – place the rock sample into the smaller can and place the larger
can over it. Shake the can for 10 minutes (2 shakes per second.)
Chemical Weathering – carefully place the rock sample into the Hydrochloric acid and
loosely place the lid on top. Observe the rock in the acid for 10 minutes.
5. Carefully pour the acid down the drain with lots of water. Remove the rock sample & dry it.
Measure the new mass of the rock sample.
6. Calculate the difference in the mass before and after the test.
7. Clean up.
Data:
Mechanical vs. Chemical Weathering Data Chart
Rock Sample &
Process
Granite
(Mechanical)
Granite
(Chemical)
Sandstone
(Mechanical)
Sandstone
(Chemical)
Limestone
(Mechanical)
Limestone
(Chemical)
Marble
(Mechanical)
Marble
(Chemical)
Mass Before (g)
Mass After (g)
Total Difference in
Mass (g)
Analysis:
- Create a BAR GRAPH (Before and after masses for each rock & process)
Answer the following:
- Which rocks were affected the most by mechanical weathering?
- Which rocks were affected the most by chemical weathering?
- Explain why a rock could gain mass in the experiment.
- What errors did you have?
Conclusion: (short paragraph)
- Which rock was affected the most by weathering?
- Which rock type (igneous, sedimentary, or metamorphic) is effected the most by weathering
and why?
- Explain the relationship between the independent & dependent variables.