Chemistry

Module #1: Electrochemistry – Friday November 4, 2011

The second week of Project START began with a bang, or more precisely a crack of electricity, that is. The students began with a brief lesson about circuits, and what causes certain things to conduct electricity, while others do not. This was shown with a fun demonstration, by using various solutions, and later vegetables, to close a circuit, we could see which conducted electricity the best. Things with a lot of electrolytes, like powerade and a pickle, conducted electricity the best and made the light bulb glow the brightest. After that, the students learned about the two different kinds of chemical cells: voltaic, or spontaneous, cells and electrolytic, or non-spontaneous, cells. The voltaic cells coated the piece of zinc in copper immediately, while the electrolytic cell needed some outside help from a power supply to force the copper onto other copper. In this case, we used pennies and nickels, both made mostly of copper, to show electroplating, and in the end several students walked away with “penny-plated” nickels, which looked bronze, due to the electrolytic cell.

Module #2: Acid-Base Chemistry – Friday November 18, 2011

The students reacted vinegar and baking soda in a bottle, producing carbon dioxide and water by a multi-step reaction. They collected the carbon dioxide by placing a balloon over the reaction bottle. Our START team then took dilute sodium hydroxide, and we observed that the basic solution made the indicator phenolphthalein turn pink. We took the balloons filled with carbon dioxide and allowed the gas to flow through a straw into the pink, basic solution. This lowered the pH and the solution became clear! This was an example of how Le Chatelier’s principle can be applied to the carbonic-acid-bicarbonate buffer system, the most important physiological buffer.

Module #3: Forensics – Friday November 18, 2011

In week three, the students of I.S. 143 had a whodunit to solve. Someone broke in to Michael Jordan’s home and stole his special pair of basketball sneakers! And it was up to the special investigators to figure out who was the thief. A list of suspects were provided to the students based on surveillance footage, and a note found at the scene allowed them to determine which pen was used, and therefore to take the fingerprints from the pen and find the criminal. First, the students were given an overview of fingerprints, and were given the opportunity to use a special technique called cyanoacrylate fuming, which uses super glue to cause fingerprints to become mostly permanent, to better study their own prints. Once they were familiar with the different types of fingerprints, the students were given the different pens found at the scene and performed a chromatographic separation on the inks to see which one matched the pattern of the ink found on the note. Using these two techniques, the students were able to successfully identify the crook, and force him to return the shoes to their rightful owner.

Module #4: Electrochemistry – Friday December 2, 2011

The group presented the idea of voltage by describing the concept of potential energy in an intuitive way, with everyday life examples of electric energy use. We experimented with various fruits and vegetables, namely lemons, pickles and potatoes, to see which contained the most aqueous electrolytes to be able to conduct electricity and confer the least resistance. We also spoke about circuits and current. We showed how the ionic solutions could be used as an electrochemical battery through the oxidation of elemental metal, or simply a path of resistance for the current, by alternating between zinc and copper electrodes.

Module #5: Ice Cream Factory (Freezing Point Depression) – Friday December 2, 2011

Module #6: Trip To Citromax (Flavor Chemistry and Solubility) – Friday December 9, 2011

Click here for more Citromax pictures

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s