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Sources of Air Pollution
Published in Subhash Verma, Varinder S. Kanwar, Siby John, Environmental Engineering, 2022
Subhash Verma, Varinder S. Kanwar, Siby John
The concentration of other pollutants is usually expressed in terms of mass per unit volume of air. On a mass basis, the concentration of a pollutant is expressed as micrograms of pollutant per cubic metre of air, μg/m3. For a gaseous pollutant, concentrations expressed in ppm on a volume basis can be converted to a mass basis by knowing the volume of gas per unit mole. As evident from gas laws, volume per unit mole is influenced by the temperature and pressure of the gas. According to Avogadro’s law, one mole of any gas occupies the same volume as one mole of any other gas at the same temperature and pressure. At standard conditions of temperature (273 K or 0°C) and pressure (1 atmosphere or 760 mm Hg), this volume is 22.4 L/mol. However, most regulations for ambient air quality are referenced at 25°C and 1 atm, with a corresponding volume of 24.5 L/mol. The L/mol at various other ambient air conditions can be converted using the following formula.
The Groundwater Geochemical System
Published in William J. Deutsch, Groundwater Geochemistry, 2020
For the purpose of understanding geochemical reactions in the environment, it is necessary to convert typical laboratory concentration units of milligrams per liter or parts per million to a scale that employs units of moles per liter or moles per kilogram. A mole refers to the number of atoms or molecules of a solute in the solution. One mole corresponds to Avogadro’s Number (6.022 × 1023) of atoms or molecules of the constituent and has a mass equal to the atomic or molecular weight of the constituent. For example, the atomic weight of carbon is 12; therefore 12 grams of carbon (one mole) contain 6.022 × 1023 atoms of carbon. The molecular weight of carbonate (CO32−) is 60; therefore, 60 grams of carbonate contain 6.022 × 1023 molecules of carbonate.
The Ideal Gas
Published in Irving Granet, Jorge Luis Alvarado, Maurice Bluestein, Thermodynamics and Heat Power, 2020
Irving Granet, Jorge Luis Alvarado, Maurice Bluestein
It is apparent from Equation 6.12 that for a given pressure and temperature, a mole of any gas will occupy the same volume. Quite often, the term standard state appears in the engineering and scientific literature, and some confusion exists as to its specific meaning. This is due to the lack of general agreement on the definition of temperature and pressure at this state. The most common standard state in use is 32°F and 14.7 psia. For this state, it will be found that 1 lbm mol occupies 358 ft.3 or 22.4 L/g mol. The use of the term standard state should be avoided unless the conditions of this state are specified.
An improved correlation for thermophysical properties of binary liquid mixtures
Published in Chemical Engineering Communications, 2023
Gustavo A. Iglesias-Silva, José J. Cano-Gómez, Mariana Ramos-Estrada, Kenneth R. Hall
This property is the total volume of one mole of a substance at a specified pressure and temperature. In the case of the molar volume of liquids, the functionality with respect to composition is almost linear for a majority the systems. However, the excess volume can have positive and negative deviations simultaneously. Such is the case for n-nonane + 1-nonanol (2) at 323.15 K (Bravo-Sánchez et al. 2010a) and acetonitrile (1) + ethanol (2) at 298.15 K (Belda Maximino 2009). The first system has excess molar volume with negative deviations from ideality near pure n-nonane, and the second system has positive and negative deviations equally distributed as shown in Figure 9. Again, all equations correlate the molar volume within its uncertainty, but as shown in the figure, Equation (4) cannot predict positive and negative deviations or vice versa. In all cases n = 1.