We remember the high school chemistry days of Bunsen burners, volumetric flasks, pipettes, beakers and test tubes. DuBois Central Catholic students will remember theirs as well. Why is chemistry class so memorable? Because when students prove what has been taught, it's learning in action.
Hands-on learning labs are an important part of the Chemistry I and II classes offered at DuBois Central Catholic School. While Chemistry I and II focused on different concepts during the labs, both used coins as their primary testing element.
Students in Chemistry I studied the concepts of cohesion, adhesion, surface tension and hydrophobic, or "water-fearing" dipole molecules, and decided to put different liquids to the test to prove the concepts. To determine the liquid with the highest surface tension, attributed to both adhesion and cohesion, students used droppers filled with various liquids and placed them on the surface of a coin (pennies in this case) for measurement. Three liquids were tested - water, soapy water, and alcohol - and water was determined to be the surface tension winner!
While in Chemistry II, students were focusing on the transfer of electrons between two substances, one solid and one liquid, known as an "electrochemical reaction". In their lab, students proved the reaction that occurs when coins naturally tarnish over time. Sulfur powder and sodium hydroxide were applied to silver coins causing them to turn black, or tarnish the coin - a natural reaction that occurs when silver is exposed to sulfur substances in the air. Various coins with different silver content were tested and evaluated.
Senior Andrew Reiter provided close up photographs of the sulfur and silver chemical reaction during his lab work!
Fun Fact:
The reaction with sulfur powder and sodium hydroxide creates the same reaction that occurs when coins tarnish over decades, and centuries sometimes, but speeds it up to occur in a matter of seconds. Many coin collectors (numismatists) value coins that have tarnished into rainbow or other aesthetically pleasing colors. Some toning occurs naturally over time while others are manipulated in this fashion. “Artificial versus natural” toning has been a huge area of debate in the numismatic community.