The non-italicized font represents additional information included to support the teacher’s understanding of the content being introduced within the CELL.

ANALYZE IT

Instruct students to complete the Analysis Questions in their SDRs then discuss them as a class. Use the suggested responses below to guide students’ answers.

Discuss the following questions after Trial 1 in the Student Data Record.

• Describe the physical properties of the marble chips. Student answers will vary. The marble chips can be described as grayish-white and hard.

• Did you successfully physically weather the marble chips? Were you able to reduce them to smaller pieces? Student answers will vary. No, we could not physically weather the marble chip and reduce them to smaller pieces.

• Why did you have difficulty reducing the chips to smaller pieces? Student answers will vary. It was difficult to reduce the size to smaller pieces because the marble was too hard.

• How long would it take to naturally physically weather the marble chips and reduce them to smaller pieces? Student answers will vary. It would take thousands or millions of years to reduce them to smaller pieces.

Discuss the questions after Trial 2 in the Student Data Record.

• Is a chemical reaction taking place between the hydrochloric acid and the marble chips? Student answers will vary. Yes, a chemical reaction is taking place between the hydrochloric acid and the marble chips.

• What observations suggest that a chemical reaction is taking place? Student answers will vary. Bubbles of carbon dioxide gas are produced suggesting that a chemical reaction is taking place. Very small pieces of material are falling off the marble chips and resting on the bottom of the flask.

• What observation suggests that not all the marble is reacting with the acid? Student answers will vary. The pieces falling off the marble chips do not appear to be reacting with the acid.

• Do the marble chips consist only of calcium carbonate? Why? There is some material that is not reacting with the hydrochloric acid suggesting that the marble chips do not consist entirely of calcium carbonate.

Discuss the questions after Trial 3 in the Student Data Record.

• Is a chemical reaction taking place between the hydrochloric acid and the calcium carbonate powder? Student answers will vary. Yes, a chemical reaction is taking place between the hydrochloric acid and the calcium carbonate powder.

• What observations suggest that a chemical reaction is taking place? Student answers will vary. Bubbles of carbon dioxide gas are produced suggesting that a chemical reaction is taking place.

• Which reaction produced carbon dioxide gas more rapidly? The reaction of the calcium carbonate with hydrochloric acid produced carbon dioxide gas more rapidly.

• Which reaction contained the smaller pieces of solid reactant, the reaction of the marble chips, or the calcium carbonate powder? The reaction containing the calcium carbonate powder had the smaller pieces of solid reactant.

• What is the relationship between the size of the particles and how fast chemical weathering takes place? Why? The smaller the size of the particles the faster chemical weathering takes place. More of the rock material is exposed to chemical weathering when the particle size is small.

GET FOCUSED

Instruct students to complete the Focus Questions in their SDRs then discuss them as a class. Use the suggested responses below to guide students’ answers.

• How are physical and chemical weathering different? Rocks are physically weathered by breaking them into smaller and smaller pieces. Rocks are chemically weathered when compounds in the rock react chemically with another chemical.

• How do physical and chemical weathering combine to weather rocks? By breaking rocks into smaller pieces, physical weathering exposes more of a rock’s surface to chemical weathering. The combination of the two speeds the overall process of weathering.