Experiment 3: Effects of a hydrophobic surface

In this experiment I tested the hypothesis that the boiling temperature is lower in a vessel with a water-repellent (hydrophobic) surface. This goes back to Marcet's report from 1842 that he was able to lower the boiling temperature by coating his glass vessels with sulphur. Instead of sulphur, we used Me3SiCl (trimethylsilyl chloride) to make an ordinary glass beaker hydrophobic. The boiling temperature in this "silanized" beaker was significantly lower than in an untreated beaker, and the boiling behaviour was very much like that in the Teflon-coated pot. The qualitative behaviour was very similar to boiling in the Teflon-covered pot, with numerous bubbles forming easily from a very low temperature and crowding around at the bottom surface. To confirm that nothing strange had happened to the water, I poured out the same water to an ordinary beaker and boiled it again. The ordinary kind of boiling behaviour and temperature was observed again, as in the later stages of boiling in Experiment 1.

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