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”

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”?

What happened in the 80’s?

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) 1H2(g) +1 Zn2+(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

Homework

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