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For example, the conversion factor between a mass fraction of 1 ppb and a mole fraction of 1 ppb is about 4.7 for the greenhouse gas CFC-11 in air (Molar mass of CFC-11 / Mean molar mass of air = 137.368 / 28.97 = 4.74). For volume fraction, the suffix "V" or "v" is sometimes appended to the parts-per notation (e.g. ppmV, ppbv, pptv).
Gutmann, a chemist renowned for his work on non-aqueous solvents, described an acceptor-number scale for solvent Lewis acidity [4] with two reference points relating to the 31 P NMR chemical shift of Et 3 PO in the weakly Lewis acidic solvent hexane (δ = 41.0 ppm, AN 0) and in the strongly Lewis acidic solvent SbCl 5 (δ = 86.1 ppm, AN 100).
The amount of pollutant present in air is usually expressed as a concentration, measured in either parts-per notation (usually parts per billion, ppb, or parts per million, ppm, also known as the volume mixing ratio), or micrograms per cubic meter (μg/m³).
As an example, given a concentration of 260 mg/m 3 at sea level, calculate the equivalent concentration at an altitude of 1,800 meters: C a = 260 × 0.9877 18 = 208 mg/m 3 at 1,800 meters altitude Standard conditions for gas volumes
The equation can only be applied when the purged volume of vapor or gas is replaced with "clean" air or gas. For example, the equation can be used to calculate the time required at a certain ventilation rate to reduce a high carbon monoxide concentration in a room.
Suppose there are known concentrations of nickel in a set of calibration solutions: 0 ppm, 1.6 ppm, 3.2 ppm, 4.8 ppm, 6.4 ppm, and 8 ppm. Each solution also has 5 ppm yttrium to act as an internal standard. If these solutions are measured using ICP-OES, the intensity of the yttrium signal should be consistent across all solutions.
The Henderson–Hasselbalch equation can be used to estimate the pH of a buffer solution by approximating the actual concentration ratio as the ratio of the analytical concentrations of the acid and of a salt, MA. The equation can also be applied to bases by specifying the protonated form of the base as the acid.
In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration. [1]