1. Do Now: What do you know about coins? How might their history result in changes in their weight? Use your lab notebook and title this “The Penny Lab”

2. How does the mass of a penny change over time? Mass 5 at a time from each decade and take the average Go ahead – ask yourself “why”?

3. What happened in the 80’s?

4. Question: What is different about a post-1982 penny vs. a pre-1982 penny? Design a controlled experiment involving quantitative data to answer this. Possibly useful information: 2HCl(aq) + 1Zn(s)  1H 2 (g) +1 Zn 2+ (aq) + 2Cl -1 (aq) HCl(aq) + Cu(s)  No Reaction Materials Available: Balances 6 M HCl Pennies (use one from before 1982 and one after) Metal Files Beakers Graduated Cylinders

5. Homework One person needs to come to etch pennies and put penny in HCl after school 168, 172 from Zumdahl