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At 10 000 ppm the solution is a deep red colour. As the concentration decreases the colour becomes orange, then a vibrant yellow, with the final 1 ppm sample a very pale yellow. In science and engineering , the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities , e.g. mole fraction or ...
Atmospheric pollutant concentrations expressed as mass per unit volume of atmospheric air (e.g., mg/m 3, μg/m 3, etc.) at sea level will decrease with increasing altitude because the atmospheric pressure decreases with increasing altitude. The change of atmospheric pressure with altitude can be obtained from this equation: [2]
Some express the concentrations as ppmv (parts per million by volume) and some express the concentrations as mg/m 3 (milligrams per cubic meter), while others require adjusting or correcting the concentrations to reference conditions of moisture content, oxygen content or carbon dioxide content.
where TDS is expressed in mg/L and EC is the electrical conductivity in microsiemens per centimeter at 25 °C. The conversion factor k e varies between 0.55 and 0.8. [5] Some TDS meters use an electrical conductivity measurement to the ppm using the above formula. Regarding units, 1 ppm indicates 1 mg of dissolved solids per 1,000 g of water. [6]
For some usage examples, consider the conversion of 1 SCCM to kg/s of a gas of molecular weight , where is in kg/kmol. Furthermore, consider standard conditions of 101325 Pa and 273.15 K, and assume the gas is an ideal gas (i.e., Z n = 1 {\\displaystyle Z_{n}=1} ).
1120 mg/kg (rat, oral) 1000 mg/kg (rabbit, oral) 710 mg/kg (mouse, oral) [2] LC 50 (median concentration) ... TWA 10 ppm (40 mg/m 3) [1] IDLH (Immediate danger) 1400 ...
1000 mg/kg (rabbit, oral) 700 mg/kg (mouse, oral) 1720–1970 mg/kg (rat, oral) [7] NIOSH (US health exposure limits): PEL (Permissible) TWA: 3 ppm (6 mg/m 3) [6] REL ...
The result is expressed in mg/kg body mass. Determining Acute LD 50 For purposes of classifying and assigning packing groups to mixtures possessing oral or dermal toxicity hazards according to the criteria in 49CFR 173.133(a)(1), it is necessary to determine the acute LD50 of the mixture.