Four teachers joined me Jan. 7th to talk about their favorite demos. We started with a request for demonstrations on solubility and intermolecular forces, and variations of the "mix-water-and-alcohol" phenomenon were offered. Mixing the two in a small diameter glass tube showed  the most dramatic reduction in volume (fill half with water, then the other half with alcohol, cap and mix), while doing it in a graduated cylinder allowed a quantitative measurement of the reduction. We wondered how much difference in reduction would result from using different alcohols, and some suggested coloring the water. Also, it was was noted that adding salt would reconstitute separate alcohol and saltwater layers.

   We then touched on the reduction of copper oxide to copper (see Royal Society video here) and of malachite (see this Royal Society video) and noted a good manual on microscale gas experiments that includes "gassing copper" might still be around (Microscale Gas Chemistry by Mattson, Anderson and Mattson). The conversation also included favorite silver nitrate demos and a cool gas law demo: connect a small balloon and a big balloon with a stopcock. Predict what happens when you open the stopcock. Surprise! The gas from the small balloon rushes into the larger balloon. Hmmmm.

   Unfortunately I botched the video so this one is not available. Sigh.

The next ChemChat open discussion will be held Feb. 12th and the topic is "Electrochemistry". Registrations are open under "Events".

- Sue Klemmer, ChemChat facilitator