MHS Chemistry
Mass Percent Copper in Pennies


In this experiment, you will be carrying out a quantative chemical analysis of new pennies (as determined in a previous lab about pennies).  "Quantative" means that you will be making careful numerical measurements.

Concentrated acids can cause severe burns.  You must wear goggles during this lab


super-shears concentrated hydrochloric acid
large test tube balance

Procedure - Mass Percent Copper in a Penny
DAY 1 - Record the mass of one of the new pennies, then scratch through it's copper surface.  Place it in a large labeled test tube and submerge it in about 5 centimeters of concetrated hydrochloric acid.  Leave it in a test tube rack and observe for a few minutes, then store it in your class's cabinet.

DAY 2 - Carefully observe the penny in test tube, then remove it by pouring the excess acid into the waste collection jar in the front of the room. Gently rinse it in the test tube with plenty of tap water.  Finally, gently examine the penny, and record your observations.  Leave the penny to dry overnight.

DAY 3 - Record the mass of your penny. Calculate the % mass of the orginal penny that was copper.


All acid waste should be disposed  of according to your teacher's instructions.  Thoroughly clean your lab bench with a sponge dipped in soapy water at the front sink.

[Mass Percent Copper in Pennies score sheet][MHS Chem page]