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Challenge #3: Lab Worksheet #2

Station Two: Let’s Spread Out At This Station!

Date of Investigation:

Name of Scientist:

Name of Recorder:

Purpose: The purpose of this lab investigation is to observe how the change in surface area of a piece of chalk changes the rate at which it reacts.
Hypothesis: If the surface area of the chalk is smaller then the rate at which chalk reacts will (increase or decrease).

Materials:

• Safety glasses, aprons and gloves
• One 100 mL beaker labeled with 0.1 M HCl_(aq)
• Two small 50 mL beakers
  • Label beaker one for the uncrushed chalk
  • Label beaker two for the crushed chalk
• Two equal pieces of chalk (approx. 2 cm)

Procedure:

1. First read ALL of the procedure before you begin.
2. Place a 2 cm piece of chalk into the small beaker labeled one.
3. Add hydrochloric acid (HCl_(aq)) carefully to the 10 mL line on the beaker.
4. Start the stopwatch.
5. Stop the stopwatch when no more bubbles are produced.
6. Record the time of the reaction (in seconds) in the Observation Chart on the following page.
7. Pour the contents of this beaker into the waste container.
8. Crush the second piece of chalk using the mortar and pestle.
9. Using a spoon, add all of the crushed chalk into the beaker labeled two.
10. Add hydrochloric acid (HCl_(aq)) carefully to the 10 mL line on the beaker.
    
11. Start the stopwatch.
12. Stop the stopwatch when no more bubbles are produced.
13. Record the time of the reaction (in seconds) in the Observation Chart below.
14. Pour the contents of this beaker into the waste container.
15. Clean up your station. Complete the checklist below before proceeding to the next station.
    • Rinse all beakers with a little distilled water.
    • Wash the counter space.
    • Wash your hands.