Amalgam (chemistry) with copper. A nitric acid solution of salts under investigation is applied to a piece of copper foil, and any mercury ions present will leave spots of silvery-coloured amalgam. Silver ions leave similar spots but are easily washed away, making this a means of distinguishing silver from mercury. The redox reaction involved where mercury oxidizes the copper is: Dental amalgam has been studied and is generally considered to be safe for humans, though the validity of some studies and their conclusions have been questioned. Amalgam (chemistry) An amalgam is an alloy of mercury with another metal, which may be a
Solution of Schrödinger equation for a step potential disappears in the context of quantum field theory. The Heaviside step potential mainly serves as an exercise in introductory quantum mechanics, as the solution requires understanding of a variety of quantum mechanical concepts: wavefunction normalization, continuity, incident/reflection/transmission amplitudes, and probabilities. A similar problem to the one considered appears in the physics of normal-metal superconductor interfaces. Quasiparticles are scattered at the pair potential which in the simplest model may be assumed to have a step-like shape. The solution of the Bogoliubov-de Gennes equation resembles that of the discussed Heaviside-step potential. In the superconductor normal-metal case this gives rise to Andreev reflection.