Download Lab: Exploring Chemical Weathering

Lab: Exploring Chemical Weathering
Objective: To recreate the effects of chemical weathering on rocks of varying composition. The final report
will be a 5-7 page double spaced, 12-pt font lab report following the guidelines in “How to Write a Lab Report”.
The discussion questions should be incorporated into the discussion.
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Materials:
Rock samples
Beakers
Cheesecloth
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wash bottle
balance
1M Sulfuric Acid
Procedure:
(1) Put 1 rock sample in each beaker. Rinse the rock sample with clean water to remove dust and
loose grains. Repeat several times for each sample.
(2) Find the mass of the rock sample and record.
(3) Measure 100ml of Sulfuric acid and pour into beaker. The solution should completely cover
the sample.
(4) For the 2nd observation, pour off the acid solution. Use cheesecloth to make sure no rock
samples fall out of the beaker.
(5) Rinse rocks several times with fresh water and drain.
(6) Measure the mass of the rock contents again. Record this information in the table.
(7) Add 100ml of Sulfuric acid to each sample beaker and set aside until the next day.
(8) Follow the same procedure for 4 consecutive readings. Record results in data table.
(9) On the last day, allow the sample to dry over the weekend. Record the final mass on Monday.
Table- Rate of Weathering
Rock
Sample
Sample
1
Sample
2
Sample
3
Combined Combined
Mass
Mass
Day 1
Day 2
Net
Change
Combined
Mass
Net
Change
Combined
Mass
Net
Change
Combined
Mass
Net
Change
(1-2)
Day 3
(2-3)
Day 4
(3-4)
Day 5
(4-5)
Discussion Questions:
1. Which of the 3 rock samples weathered the most? How does your data support this conclusion?
2. Which of the 3 rock samples weathered the least? How do you explain the result?
3. What properties of the samples may play a part in their resistance to chemical weathering? Which
property do you think was most significant?
4. Did the rate of weathering change in any of the samples during the course of the investigation? If so,
explain and suggest what may have caused this.
5. What primary process of chemical weathering does this exercise most closely simulate?
6. In addition to the difference of each of the 3 rock types, what other properties might influence the rate of
chemical weathering in each of the samples?
7. Which of the 3 rock types in this investigation would be best to construct a building in an area with
heavy industrial emissions and car exhaust? Why?
8. Discuss the data you collected from the soil sample that you collected in class and analyzed with the
permeability test, soil ribbon and nutrient analysis.
9. What are some examples of chemical weathering evident in your area? Describe what processes may
have been responsible for the weathering.