How do you convert ppm to grams?



Template: DISPLAYTITLE: parts per million The English expression parts per million (ppm, in German Parts per million) stands for the number 10−6 and is used in science for the millionth part, just as percent (%) stands for the hundredth part. However, like the international standard ISO 31-0 "Quantities and units - Part 0: General principles" from 1992, the IEC 1978 recommended avoiding the ppm. This is mainly in order to prevent the risk of misunderstandings with the analogously formed terms ppb and ppt. Because "billion" and "trillion" mean 10 in American usage9 (billion) and 1012 (trillion) while in the German 1012 (for trillion) and 1018 (for trillion) mean. Therefore, any information in one of these units should always be treated with caution.

Nevertheless, especially when measuring the concentration of natural gas in air, the proportions of the gas are measured with gas concentration measuring devices or gas detection devices in ppm or, in the case of higher concentrations, in percentages or proportions by volume. A mass fraction can be specified in milligrams per kilogram, a volume concentration in milliliters per cubic meter or a molar fraction in micromoles per mol. Another area of ​​application is the specification of error rates in the context of quality management. In automotive production in particular, there are often specifications for permissible ppm rates.

In geodesy, the accuracy of devices for measuring distances is often given in ppm. So here is an indication of Millimeters per kilometer meant. In NMR spectroscopy, the ppm is used to indicate the chemical shift. In chemistry, the ppm is often used incorrectly when specifying the concentration of aqueous solutions. Here, 1 ppm = 1000 ppb means just 1 mg / l.

Volume mixing ratios are adjusted by a v (for example ppmv, ppbv) marked. For ppmv also becomes the abbreviation vpm used.

conversion

  • percent = 10−2 = 10,000 ppm = parts per hundred
  • Per mille = 10−3 = 1,000 ppm = parts per thousand
  • ppm = 10−6 = Parts per million
  • ppb (parts per billion) = 10−9 = Parts per billion
  • ppt (parts per trillion) = 10−12 = Parts per trillion
  • ppq (parts per quadrillion) = 10−15 = Parts per quadrillion

If the immission quantity is given as a mass fraction per volume, e.g. in µg per m³ air, the conversion to ppm is based on the ratio of the number of molecules.

Example: 0.1 µg of lead in one m³ of air corresponds to (0.1 * 10−6 / 207) mol of lead in (1 / 22.4 * 103 ) moles of air. So there are about 10 for one lead atom11 Air molecules (thus 0.1 µg lead / m³ air corresponds to about 10 ppt lead in air). The following were used for this calculation: molar mass of lead = 207 g / mol and number of gas particles at 0 ° Celsius per liter = 1 / 22.4 mol (with pV = nRT).

See also

Category: Unit of Measure