Purpose:  The purpose of this lab is to discover, by analogy, how chemist count atoms and molecules and to determine the accuracy of the  “counting by weighing” method.

Hypothesis: When known quantities of particles are counted and measured, the average mass of the particles can be calculated because the “counting by measuring” method was used.

Materials:

Procedure:

1. Obtain a sample of pennies in a sealed container. Do not count the pennies. 

2. Obtain an empty container that is similar to the one containing the pennies. Obtain one additional penny. Devise a method using a balance to determine the number of pennies in the sealed container without opening it. Determine the number of pennies in the sealed container.

3. Repeat step 2 using ten additional pennies instead of one penny. Use your method to determine the number of pennies in the sealed container. 

4. Open the sealed container and count the pennies.