Chapter 12, Problem 112
What is the coordination environment of the K+ ions in the fullerene-based superconductor K3C60?
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A photovoltaic cell contains a p–n junction that that converts solar light to electricity. An optimum semiconductor would have its band-gap energy matched to the wavelength of maximum solar intensity at the Earth's surface. (b) Which of the following semiconductors absorb at a wavelength matched with maximum solar intensity? CdTe with a band-gap energy of 145 kJ/mol or ZnSe with a band-gap energy of 248 kJ/mol.
Wide band-gap semiconductors have a band gap between 2 and 7 electron volts (eV), where 1 eV = 96.485 kJ/mol. The wide band-gap semiconductor GaN, used to construct the laser in Blu-ray DVD players, has a band gap of 3.44 eV. The material in the laser, GaxIn1-xN, has some indium substituted for gallium. (b) If the light from the device is blue, does partial substitution of indium for gallium increase or decrease the band gap of GaxIn1-xN compared to GaN?
The YBa2Cu3O7 superconductor can be synthesized by the solgel method from a stoichiometric mixture of metal ethoxides followed by heating in oxygen. How many grams of Y(OCH2CH3)3 and how many grams of Ba(OCH2CH3)2 are required to react with 75.4 g of Cu(OCH2CH3)2 and an excess of water? Assuming a 100% yield, how many grams of YBa2Cu3O7 are obtained?