by Joseph Topczewski
This past Saturday (June 4th) we were able to explore Chemistry at Market Science. Our event lived up to its name of “Atoms, Colors, and Changes in Our Chemical World!” and we explored all three in five different activities.
The first activity was centered on a color change caused by adding dry ice to water that contained a pH indicator. The dissolved CO2 (dry ice is solid CO2) formed carbonic acid and lowered the pH of the water – a reaction that we could see by color change! This is the same process that occurs when there is an increase in atmospheric CO2, which is a leading cause of ocean acidification.
The second activity helped us see two other signs of a chemical reaction and also explained some of the ecological effects of ocean acidification. In this activity we mixed clear solutions of Na2CO3 with CaCl2 and caused the precipitation of CaCO3 as a white solid – another sign of a chemical reaction! CaCO3 is the main component of clam shells and coral and these structures are biosynthesized by a similar albeit more complex process. The CaCO3 is not always stable though. As we saw by adding citric acid, the CaCO3 dissolves in acidic solutions and then bubbles form! Bubbles are gas evolution and are a third sign of a chemical reaction. This is essentially the same reaction (sped up) that causes clams and coral to struggle to form shells in an acidified ocean.
Our third activity showed how chemistry can be handy to know about with everyday experiences. The activity focused on cleaning pennies with a little bit of science. While participants struggled to clean their penny in clean water or in soapy water, exposure to some citric acid polished it right up by dissolving the outer layer of copper oxide. See chemistry can be useful.
The fourth activity asked participants to think about what we are breathing – air. As it turns out air is a gas and gases have special properties. We explored some of those such as the relationship between volume and pressure, moles of gas, and temperature. The last was the most dramatic since we shrunk the balloons in liquid nitrogen and then let them warm up in front of us. While no extra gas was added, they got a lot bigger!
The last activity was perhaps the most popular – making SLIME! After all slime is cool. Even though the slime was a lot of fun we were also able to explain what the cross linking of polymers can do to its physical properties.
I think we had a great time at the market having fun with chemistry. I hope everyone can enjoy some chemistry this week and we hope to be back again!