How Honest is Abe?

INTRODUCTION:

Today’s penny is quite different from the penny of years ago. As far back as 1864, pennies have been made up almost entirely of copper (Cu). The only exception to this was in 1943 when copper was heavily used for the war effort. For that year and that year only, the penny was made of zinc-coated steel. In 1982, the U.S. Mint changed the composition of pennies. Since then, pennies have been made with an outside coating of Copper and an inner core of Zinc (Zn). These differences in the composition of older and more recently minted pennies have resulted in differences in the penny’s characteristics, including its density, or mass per unit volume. In this experiment, you will determine and compare the densities of pennies minted before 1982 and after 1983.
Density is a physical property of matter that expresses the amount of mass an object has per unit volume. The density of a material helps to distinguish it from other materials. Since mass is usually expressed in grams and volume in cubic centimeters, density is expressed in grams/cubic centimeter (g/cm3). NOTE: 1cm3 = 1mL = 1cc


WordScreenSnapz026.jpg

PURPOSE:

In this experiment you will:
  1. determine the densities of pennies minted before 1982 and after 1983.
  2. compare the densities of pennies minted before 1982 and after 1983.


EQUIPMENT:

25 pre-1982 pennies
25 post-1983 pennies
50ml Graduated Cylinder
Paper towels
Electronic Balance


INSTRUCTIONS:

  1. Each person in your lab group must read every page in this online procedure. Along the way, there will be questions that you must answer.
  2. Designate one person in your group as the Data Recorder. This person should open the Google document Experiment 3 - How Honest is Abe? for the approved answer template.
  3. When this Google document opens, sign in to your Google account.
  4. From the FILE Menu, choose Make a copy...
  5. From the FILE Menu, choose Rename...and rename the document as follows: Exp 3 - Period (1, 3, 6, or 8) - Group #.
  6. Share this document with the members of your group and with Mr. Skubis at HSTChemistry@gmail.com.
  7. As a group, answer all questions. Remember to use complete sentences and be mindful of grammar, spelling, and punctuation.
  8. REMEMBER: **Plagiarism** is a form of **Academic Dishonesty** which carries harsh consequences. DO YOUR OWN WORK!


PROCEDURE:

Using the data table in the accompanying Google Doc, RECORD OBSERVATIONS and/or DATA for each procedure step.
  1. Work with one set of pennies at a time, either pre-1982 pennies or post-1983 pennies. Find the mass of 5 pennies from one set. Record the mass in the appropriate data table.
  2. Add 5 more pennies to the first group and obtain the mass of these 10 pennies. Record the mass.
  3. Repeat step 2, each time adding 5 more pennies to those already on the balance, until you have used all 25 pennies.
  4. Fill a 50ml Graduated cylinder to the 20ml mark with water. Be sure to use the bottom of the meniscus to measure the water level.
  5. Still working with the same 25 pennies, GENTLY drop 5 pennies into the graduated cylinder. Record the new water level in the appropriate table.
  6. Add 5 more pennies to the graduated cylinder, making the total 10. Record the new water level.
  7. Add 5 more pennies and record the water level.
  8. Repeat 7 until you have used all 25 pennies.
  9. Discard water and dry pennies with a paper towel, and either pass the pennies on or give them back to the teacher.
  10. Repeat steps 1-9 using 25 pennies in the other set of coins. Record your data in the other table.
  11. Complete your data tables.


ANALYSIS

Use the table in the approved Google Document to organize your observations and data described in the procedure. In the Analysis column, record your interpretation of what happened in each step.

FOLLOW UP QUESTIONS

Write answers for the questions in the Google Document. Remember to use whole sentences. Pay close attention to grammar, spelling, and punctuation.