Bling crib

I saw the following image of Roger Hiorns' Seizure installation over at Boing Boing and was struck by the beauty of it. The color is nice and I'm sure the artist is challenging perceptions or something, but I love the huge single crystals. I've tried to grow countless crystals for x-ray analysis with very mixed results. People tell me that growing single crystals is more of an art than a science, but one thing of which I am certain is that you need to grow them slowly. That appears to be what the artist did in this case. (It also helps that he wasn't trying to grow air-sensitive organometallic complexes.)





From the photos it appears that the artist waterproofed an apartment in an abandoned building and filled it with 80 kL of hot, saturated copper(II) sulfate (solfato di rame) solution. As the solution cooled, copper(II) sulfate pentahydrate crystallized on every surface in the room. I thought this was timely since I was playing around with copper(II) sulfate today. I dissolved it in water and added sodium carbonate to precipitate copper(II) carbonate. Then I mixed that with excess carbon and heated it in a crucible to smelt metallic copper. Maybe I'll get out the oxygen torch tomorrow and see if I can make silver from that big jar of silver chloride waste in my hood.

More photos can be found here and here.

Over the rainbow

I was in the lab yesterday drying and distilling some triethylamine for one of my projects. On a whim, I used a crystalizing dish full of copper shot instead of a heating mantle, oil bath, or sand bath. The resulting rainbow of copper brought a little joy into my day. Perhaps there is a lesson about grad school to be learned here... nah.

The rainbow resulted from the different rates of oxidation across the temperature gradient in the dish (~300 °C to 80 °C). There is a more thorough explanation for the phenomina in "Optical characterization of thin thermal oxide films on copper by ellipsometry" Derin, H.; Kantarli, K. Appl. Phys. A 2002, 75, 391–395, DOI: 10.1007/s003390100989

A copper oxide film grown thermally on a copper surface can be distinguished by the color of reflected light from the
copper oxide–copper film system. If the film grown on copper is cuprous oxide (Cu₂O), the observed color changes from purple to blue, green, yellow and red depending on oxide thickness. However, cupric oxide (CuO) grown on a copper surface is black... The reflectance spectra in the visible region for the thick copper film and copper oxide–copper structures, for different oxide thicknesses, are shown in Fig. 8. The reflectance minimum that begins to show itself after the first oxidation time shifts towards long wavelengths as the thickness of oxide film increases. The observed colors of these samples changed from green to yellow for the oxide thicknesses given in Fig. 8. These colors arise from the reflectance drop passing a minimum at wavelengths between 4000 and 6000 Å in the reflectance spectrum of the Cu₂O–Cu system. If the oxide films were CuO, the reflectance value would be zero for all wavelengths in the visible and therefore all samples of different oxide thickness would be black... The reflectance minima observed in Fig. 8 arise from the destructive interference of rays reflected from the air–copper oxide and copper oxide–copper interfaces.