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Diagram illustrating the principles used by William Wallace's eidograph. The ancient Greek engineer Hero of Alexandria described pantographs in his work Mechanics. [1]In 1603, [2] Christoph Scheiner used a pantograph to copy and scale diagrams, and wrote about the invention over 27 years later, in "Pantographice seu Ars delineandi res quaslibet per parallelogrammum lineare seu cavum" (Rome 1631).
The diamond-shaped, electric-rod pantograph of the Swiss cogwheel locomotive of the Schynige Platte railway in Schynige Platte, built in 1911 Cross-arm pantograph of a Toshiba EMU. A pantograph (or "pan" or "panto") is an apparatus mounted on the roof of an electric train, tram or electric bus [1] to collect power through contact with an ...
Countercurrent distribution is a separation process that is founded on the principles of liquid–liquid extraction where a chemical compound is distributed (partitioned) between two immiscible liquid phases (oil and water for example) according to its relative solubility in the two phases.
In a chronoamperometry, a sudden step in potential is applied at the working electrode and the current is measured as a function of time. [8] Since this is not an exhaustive method, microelectrodes are used and the amount of time used to perform the experiments is usually very short, typically 20 ms to 1 s, as to not consume the analyte.
For typical ionic solids, the cations are smaller than the anions, and each cation is surrounded by coordinated anions which form a polyhedron.The sum of the ionic radii determines the cation-anion distance, while the cation-anion radius ratio + / (or /) determines the coordination number (C.N.) of the cation, as well as the shape of the coordinated polyhedron of anions.
A mnemonic is a memory aid used to improve long-term memory and make the process of consolidation easier. Many chemistry aspects, rules, names of compounds, sequences of elements, their reactivity, etc., can be easily and efficiently memorized with the help of mnemonics.
Physical chemistry, in contrast to chemical physics, is predominantly (but not always) a supra-molecular science, as the majority of the principles on which it was founded relate to the bulk rather than the molecular or atomic structure alone (for example, chemical equilibrium and colloids).
Also called direct coulometry, the analyte is oxidized or reduced at the working electrode without intermediate reactions. [6] The working electrode is kept at a constant potential and the current that flows through the circuit is measured. This constant potential is applied long enough to fully reduce or oxidize all of the electroactive ...