Name: __________________________ Date: ___________________ Pd. ________
Mechanical vs. Chemical Weathering
Objectives:
Students will…

identify types and causes of weathering and differentiate between them.
Introduction:
The earth is in a constant state of motion, both as a planet in the solar system and as a body of interactive
systems. Many of these systems create forces that change the face of the planet. The term weathering refers to
any force that breaks down rocks and other objects in nature into smaller pieces. Erosion refers to the movement
of the parts that were broken off through the weathering process.
Mechanical weathering is when physical forces are applied to break rocks down into smaller particles.
Chemical weathering is when chemical reactions take place such as oxidation (rust). There are differences
between mechanical and chemical weathering but both serve the same purpose.
Materials:

Weathering Vocabulary

Types of Weathering
Stopwatch

1 piece of hard candy (per student)
water

2 beakers (per group)
vinegar or lemon juice

2 alka seltzer tablets (per group)
Pre-Lab (10 Points)
Read the introduction and procedure and answer the essential lab questions:
 What am I trying to find out?

How am I trying to find this out?
Procedure:
PART A: Weathering Vocabulary and picture association
You will be moving around the room to locate different weathering terms. There are two posters for each
term. You will be recording the definition for each term and drawing a picture or writing the example in the
box on the back.
Posters around the room
PART B: Mechanical and Chemical weathering matching.
Mechanical vs. Chemical Weathering
Separate the vocabulary terms, THAT ARE BELOW, into the correct mechanical and chemical weathering columns.
MECHANICAL WEATHERING
CHEMICAL WEATHERING
1. ______________________________ _____
1. _____________________________ _____
2. ______________________________ _____
2. _____________________________ _____
3. ______________________________ _____
3. _____________________________ _____
4. ______________________________ _____
4. _____________________________ _____
5. ______________________________ _____
5. _____________________________ _____
6. ______________________________ _____
Match weathering terms to weathering examples.
Frost Action
_____
A. Feldspar turns into clay
Plant Acids
_____
B. Blurred inscriptions of grave markers
Hydrolysis
_____
C. Carbonic acid dissolves rocks
Abrasion
_____
D. Large sheets of loosed rock break away from outcropping
Gravity
_____
E. Red soil or rocks
Sulfuric Acid
_____
F. Formation of potholes in winter
Oxidation
_____
G. Rocks falling from high places
Organic Activity
_____
H. Lichens growing on rocks
Wetting and Drying
_____
I. Drought causes soil to crack
Carbonation
_____
J. Rounded pebbles in a stream bed
Joint Sheeting
_____
K. Lifted sections of sidewalk along tree-lined streets
PART C: Candy Crush
1.
After looking at the pictures, discuss the similarities and differences between the pictures and the way
they’re related with the people at your table.
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2. Describe the process and where you have seen “weathering” evidence in your daily life.
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3. Take the piece of candy that Ms. Glover has handed to you and unwrap it. DO NOT PUT IT IN YOUR
MOUTH YET! (assign half of the class to briefly chew their candy before dissolving it in their mouths and the other half to NOT
chew their candy)
4. Once Ms. Glover has told you to put it in your mouth, raise your hand when you are finished eating it.
(document the time taken to dissolve each candy completely)
5. Explain to me how eating the candy has represented weathering.
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(chewed candies were MECHANICALLY weathered (increasing the surface area of the candy) before the CHEMICAL weathering
(saliva dissolving the candy) increased surface area speeds up weathering)
6. Complete the following concept map comparing the types of weathering and their causes. Also, describe
the differences between the types of causes and provide examples.
WEATHERING
Mechanical
Chemical
Definition
Definition
Definition
PART D
7. In each group, you have two beakers filled with water. One is marked “A” and has water in it. The other is
marked “B” and has vinegar in it.
a.
PREDICT: which group is chemical weathering going to occur? Explain.
__________________________________________________________________________
__________________________________________________________________________
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8. Separate and unwrap the tablets. Two people will need to be time keepers and two people will be in charge
of dropping the tablet in and saying stop.
9. Place one alka seltzer tablet into each beaker and watch to see which one dissolves quicker. Record the
time in seconds.
Beaker A____________________ Seconds
Beaker B_____________________seconds
10. Which liquid (Beaker “A” or Beaker “B”) contained a substance that would chemically weather the tablets?
How would mechanically weathering (crushing) the tablets beforehand dropping them into the beaker speed
up the results? Explain how you came up with this conclusion. Was your “prediction” correct?
________________________________________________________________________________
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Essential Lab Questions:
1.
What types of weathering are prevalent in Edgewood compared to other parts of the country?
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2. Thinking about the Grand Canyon, explain what type(s) of weathering that has occurred. How do you know?
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