Rock Shake (2) Name___________________ Date__________ Background: Which do you think will weather faster, a rock attacked by plant acids or a rock in the rushing waters of a stream? Many factors affect the rate at which rock weathers. In this lab you will compare the rates of weathering that take place under different conditions. Problem: How will shaking and acid conditions affect the rate at which limestone weathers? Materials: Water Marking pen/pencil Balance acid Paper towels Graduated cylinder Masking tape Small pieces of water soaked limestone 2 Pieces of thin cloth 4 cups Goggles tin foil Procedure: Part 1 - Day 1 1. Label the containers A, B, C, and D. 2. Separate the limestone into 4 equal sets 3. Place one of the sets of limestone on the balance and record its mass in the data table as "Total Start Mass." Place stones in container A. 4. Repeat step 3 for containers B, C, and D. 5. Pour 50 mL of water into containers A and B. 6. Pour 50 mL of vinegar into containers C and D. 7. Cover all 4 cups and place in the designated area. Let sit for 24 hours. 8. Hypothesize which container will cause the most weathering. Record it in the space provided. Part 2 - Day 2 9. Transfer contents of Containers B and D into capped container. Carefully shake containers B and D for 10 minutes. Make sure each container is shaken for the same amount of time and the same intensity. Do not shake containers A and C. 10. Open container A and place a piece of thin cloth over the opening. Carefully pour out all of the water through the cloth into a waste container. Dry the pieces and record their mass in the data table. 11. Determine the change in mass and record it in the data table. 12. Repeat steps 10 and 11 for containers B, C, and D. 13. Clean up as instructed 14. Answer conclusion questions. Container Total Total mass Change in Rank mass start the next day Mass (1 most -4 least) order of weathering A (water, no shake) B (Water, shaking) C (Vinegar, No shake) D (Vinegar, shaking) Answers must be in complete sentences for full credit! Hypothesis: 1. Which container do you think will lose the most mass? (Weather the most) Conclusion questions: 1. What cup is the control in this experiment? 2. What agent (mechanical, chemical, or both) does each cup represent. A= B= C= D= 3. Did all of the cups lose mass? If not, which one did not change? 4. Did any group of rocks (A, B, C, or D) gain mass? Why do you think so? 5. Which container(s) lost the most mass? 6. Which agent (mechanical, chemical, or both) caused the most loss of mass? Support your answer with data. 7. In your opinion, what agent of weathering is most powerful at breaking down rock? Support your answer. 8. Where would you expect to find more weathering at a beach or in a pond? Why?
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