Rocks and Minerals > Rock Cycle Activities

Physical and Chemical Weathering

by Deborah Hanuscin

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Concept: Weathering

Two types of weathering are physical and chemical. In physical weathering, rock is simply broken down into smaller pieces. In chemical weathering, chemical reactions occur that create new substances.

Objective:

Students will be able to define and distinguish between physical and chemical weathering.

Materials:

• 2 pieces of chalkboard-type chalk
• white vinegar
• water
• mortar and pestle or hammer and plastic sandwich bag
• 4 small clear containers

Procedure:

1. Label the four containers A, B, C, and D.
2. Place half a piece of chalk into container A and cover with vinegar.
3. Place half a piece of chalk into container B and cover with water.
4. Crush half a piece of chalk (use the mortar and pestle or place in a baggie and use the hammer) and place it into container C.
5. Place half a piece of chalk in container D.
6. Place the four containers in a safe place where you can observe any changes over the next few days. You may wish to continue your observations for a longer period of time to allow the vinegar and water to completely evaporate.
7. Record your observations, including any visible differences or smells you notice.

Questions:

1. What changes did you notice in the chalk in each container? How do they differ from the original piece of chalk in container D?
2. Based upon your observations, which container represents a physical change?
3. Based upon your observations, which container represents a chemical change where some new material was created? What evidence is there?
4. Where might processes such as these occur in a similar way in nature?

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