Modeling Chemical Weathering
4th grade PSI
Teacher’s Notes:
 These two simple activities model chemical weathering. They can be set up in
the classroom in two stations that groups are rotating through or having the
whole class doing both of the activities together. Either way, be sure to
encourage close observation and discussion throughout, as chemical weathering
can be tricky to understand.
 For Activity #1, the material that makes up a penny does not change. This can be
confusing, but make sure that kids understand that the ketchup or vinegar eats
away at the corrosion on the coin (the dark stuff, the film). It is not the penny that
represents a rock, but the corrosion on it (which is why the penny must be old).
 Activity #2 is a bit more straightforward. The chalk can represent a rock in nature
and the vinegar acid rain over time or another sort of chemical. If you want, you
can also have students fill one jar with water and observe how it does not do
much to the chalk. The vinegar, then, is like acid rain, not pure water, which is
what can dissolve rocks.
 Students should observe how chemical reactions in these activities break things
down – weathers them – but in a different way than mechanical weathering does.
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4th Grade PSI Science
Earth Systems
Modeling Chemical Weathering
Name: __________________________
4th grade PSI
Activity Question
How does chemical weathering work?
Before You Begin
Is it easy to change the material that something is made of?
Why or why not?
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Purpose:
During these two activities, you will see examples of chemical
weathering. In nature, chemical weathering can take many years.
In this experiment, you will simulate this process over a much
shorter time period.
Activity #1
Materials:
 an old penny
 ketchup
 vinegar
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4th Grade PSI Science
Earth Systems
Procedure:
Take an old penny and rub it with either ketchup or vinegar for
three minutes. (Choose one or the other.) After three minutes,
rinse the penny with water.
Questions
1. What happened to the dark stuff that was on the penny?
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2. The penny did not change what it was made of; so how do
you think this is like chemical weathering?
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4th Grade PSI Science
Earth Systems
Activity #2
Materials:
 clear plastic jar
 piece of chalk
 vinegar
 goggles
Procedure:
1. Put your goggles on.
2. Place a piece of chalk in the bottom of the jar.
3. Carefully pour vinegar into the jar to cover the chalk. When
pouring the vinegar, be careful not to spill any on you and do
not put your face directly over the jar. Watch closely.
Questions
1. What happened to the chalk? How did the vinegar react with
the chalk?
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2. How is this like chemical weathering?
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4th Grade PSI Science
Earth Systems