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Polyacrylonitrile (PAN) is a synthetic, semicrystalline organic polymer resin, with the linear formula (CH 2 CHCN) n. [2] ... and PAN's fiber chemistry. Its ...
The natural concentration of PAN in the atmosphere is below 0.1 μg/m 3. Measurements in German cities showed values up to 25 μg/m 3. Peak values above 200 μg/m 3 have been measured in Los Angeles in the second half of the 20th century (1 ppm of PAN corresponds to 4370 μg/m 3). Due to the complexity of the measurement setup, only sporadic ...
The existence of free, gas-phase phosphorus mononitride was confirmed spectroscopically in 1934 by Nobel laureate, Gerhard Herzberg, and coworkers. [8] J. Curry, L. Herzberg, and G. Herzberg made the accidental discovery after observing new bands in the UV region from 2375 to 2992 Å [9] following an electric discharge within an air-filled tube that had been earlier exposed to phosphorus.
In organic chemistry, peroxyacyl nitrates (also known as Acyl peroxy nitrates, APN or PANs) are powerful respiratory and eye irritants present in photochemical smog. They are nitrates produced in the thermal equilibrium between organic peroxy radicals by the gas -phase oxidation of a variety of volatile organic compounds (VOCs), or by aldehydes ...
[1] [2] [3] Introduced by Gilbert N. Lewis in his 1916 article The Atom and the Molecule, a Lewis structure can be drawn for any covalently bonded molecule, as well as coordination compounds. [4] Lewis structures extend the concept of the electron dot diagram by adding lines between atoms to represent shared pairs in a chemical bond.
Quantum chemistry: Douglas Hartree and Vladimir Fock: Hasegawa–Mima equation: Plasma physics: Akira Hasegawa and Kunioki Mima: Hazen–Williams equation: Hydraulics, Irrigation: Hazen and Williams Helmholtz equation: Electromagnetic radiation, Seismology, Acoustics: Hermann von Helmholtz: Henderson–Hasselbalch equation: Chemistry
Historically, the mole was defined as the amount of substance in 12 grams of the carbon-12 isotope.As a consequence, the mass of one mole of a chemical compound, in grams, is numerically equal (for all practical purposes) to the mass of one molecule or formula unit of the compound, in daltons, and the molar mass of an isotope in grams per mole is approximately equal to the mass number ...
This is a list of unsolved problems in chemistry. Problems in chemistry are considered unsolved when an expert in the field considers it unsolved or when several experts in the field disagree about a solution to a problem.