chemistry, Experiments, Physics, Simon teaching, Simon's sketch book, Together with sis

Chemistry Experiments: Polarized light iridizes crystals

Today we have made beautiful rainbow chrystals! Polarized light iridizes sodium thiosulfate crystals, so we made the crystals in between two polarizing films and then observed them through the microscope. In the video, Simon also explains how polarizing film works.

From the scientific description at the MEL Science website: Sodium thiosulfate crystals contain five molecules of water per one unit of sodium thiosulfate Na2S2O3. Interestingly, when heated, the crystals release the water, while sodium thiosulfate dissolves in this water. This solution solidifies rapidly when cooling, forming beautiful crystals. If these crystals are put between polarizing films, they take on an iridescent sheen. This is because the polarizing films only let light with certain characteristics through, and this light in turn “iridizes” the otherwise-colorless sodium thiosulfate crystals.

chemistry, Experiments, Physics, Together with sis

MEL Chemistry Box number 3: Artificial Snow and growing crystals on a Xmas tree

Our third MEL Science box arrived back in August, when we were on vacation. We have already tried two experiments from the box, both perhaps more suitable for winter. Instant Snow, using sodium polyacrylate (the stuff you can find in diapers):

And growing salt crystals on a paper Christmas tree: