Pushpa Bahl [Collins HS] TITRATION
Pushpa provided several handouts of background information and directions for a hands-on exercise we would be doing later. She announced that there was a "scientific mistake" on the directions sheet and offered a $2 reward (which she showed us) to the first person to discover it. After several false alarms the oldest person in the room noticed that the word "millimeters" had been used where "milliliters" was intended and claimed the prize. Pushpa described a "drop counting" method for doing titration, which is safer and less expensive (though less precise) than using burettes. She then said we would be doing an acid-base, neutralization reaction (Acid + Base ® Salt + Water), specifically:
Carl Martikean [Wallace HS, Gary IN] CATALYSTS
Carl wrote these words Jersey, Guernsey, ***Angus on the board and asked us what it was. After a couple of rejected answers, the oldest person present (who had seen this before), said "that looks like a cattle list". Carl said, "that's right!--- and today I am going to use some catalysts". --- this was followed by loud groans! He then demonstrated several ways to catalyze the decomposition of hydrogen peroxide , H2O2, using a more concentrated solution (probably 6% by weight and sold as a bleach in hair product shops) than the 3% solution sold at drugstores. In each case he added some bubble soap solution to the hydrogen peroxide, before adding the catalyst, to produce a foam when oxygen gas is formed (the reaction produces oxygen gas and water). The catalysts used were dry yeast (which contains biological catalysts called enzymes), manganese dioxide [MnO2] (with a surface that can act as a catalyst), and some sodium iodide [NaI] (where the iodide ion [I-] is present), into the catalyst. He used the "glowing splint" method to verify that the gas formed really was oxygen. He then demonstrated another way to produce oxygen by adding some cobalt chloride [CoCl2] solution to household bleach. Finally, he enlisted our help in cleaning some grungy looking pennies by immersing them in acetic acid solution (CH3COOH: vinegar); not much happened until we added a pinch of salt (NaCl: sodium chloride) to act as a catalyst, after which the pennies sparkled like new! [*** Carl surely meant to say Aberdeen Angus, although he should not have ignored the Holstein Frisian breed -- PJ!] Nice work, Carl!
We began some informal scientific discussions, which we will follow up in our next meeting: stay tuned! See you next time (10 December)!
Notes taken by Ken Schug.