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Symbols, Terminology, and Nomenclature
Published in W. M. Haynes, David R. Lide, Thomas J. Bruno, CRC Handbook of Chemistry and Physics, 2016
W. M. Haynes, David R. Lide, Thomas J. Bruno
Energy gap* - In the theory of solids, the region between two energy bands, in which no bound states can occur. Enols, alkenols - The term refers specifically to vinylic alcohols, which have the structure HOCR'=CR2. Enols are tautomeric with aldehydes (R' = H) or ketones (R' not equal to H). [5] Enthalpy (H)* - A thermodynamic function, especially useful when dealing with constant-pressure processes, defined by H = E + PV, where E is energy, P pressure, and V volume. [1] Enthalpy of combustion* - The enthalpy change in a combustion reaction. Its negative is the heat released in combustion. Enthalpy of formation, standard* - The enthalpy change for the reaction in which a substance is formed from its constituent elements, each in its standard reference state (normally refers to 1 mol, sometimes to 1 g, of the substance). Enthalpy of fusion* - The enthalpy change in the transition from solid to liquid state. Enthalpy of sublimation - The enthalpy change in the transition from solid to gas state. Enthalpy of vaporization* - The enthalpy change in the transition from liquid to gas state. Entropy (S)* - A thermodynamic function defined such that when a small quantity of heat dQ is received by a system at temperature T, the entropy of the system is increased by dQ/T, provided that no irreversible change takes place in the system. [1] Entropy unit (e.u.) - A non-SI unit of entropy, equal to 4.184 J/K mol. Ephemeris time - Time measured in tropical years from January 1, 1900. Epoxy compounds - Compounds in which an oxygen atom is directly attached to two adjacent or non-adjacent carbon atoms of a carbon chain or ring system; thus cyclic ethers. [5] Equation of continuity - Any of a class of equations that express the fact that some quantity (mass, charge, energy, etc.) cannot be created or destroyed. Such equations typically specify that the rate of increase of the quantity in a given region of space equals the net current of the quantity flowing into the region. Equation of state* - An equation relating the pressure, volume, and temperature of a substance or system. Equilibrium constant (K)* - For a chemical reaction aA + bB cC + dD, the equilibrium constant is defined by: K= aC c aD d aA a aB b
Development and qualification of a VH-TDMA for the study of pure aerosols
Published in Aerosol Science and Technology, 2019
Christopher R. Oxford, Charles M. Rapp, Yang Wang, Purushottam Kumar, Daniel Watson, Julianna L. Portelli, Eric A. Sussman, Steven Dhawan, Jingkun Jiang, Brent J. Williams
Three primary TDMA experiments are used to explore primary and secondary atmospheric aerosol processes. (1) For hygroscopicity, dry particles are selected by the first DMA, and these particles are placed in a humid environment. The particles absorb water by condensation, and the final diameter measured by DMA2 is related to hygroscopicity, which defines a particle’s affinity for water (Liu et al. 1978). Early hygroscopicity experiments left DMA2 under the influence of environmental temperature (Li, Montassier, and Hopke 1992; McMurry and Stolzenburg 1989). Modern TDMAs either heavily insulate the second DMA or place DMA2 and its tubing in a temperature controlled environment to increase hygroscopic measurement reproducibility (Duplissy et al. 2009). (2) For volatility, selected particles from DMA1 are placed in a heated environment to partially evaporate the condensed phase. The final diameter measured by DMA2 is related to the saturation vapor pressure of the aerosol particles (Rader, McMurry, and Smith 1987). Measuring saturation vapor pressure as a function of temperature allows the estimation of the enthalpy of sublimation or vaporization (De Nevers 2012). Volatility experiments often use a short, electrically heated tube to establish the heated experimental environment (Hong et al. 2017; Wehner, Philippin, and Wiedensohler 2002). (3) For reactions, selected particles from DMA1 are passed through a chemical reactor. The final diameter measured by DMA2 is related to either the condensation of gaseous chemical products, or the evaporation of condensed phase chemical products. From these measurements, reaction rates can be calculated (McMurry, Takano, and Anderson 1983).