Usually, in the quantitative aspect of solutions, to calculate the relationship between the mass of the solute and the mass of the solution, the quantity called “Title” or “Mass Percentage” is used.
Although, there are some cases where the mass of the solute present in the solution is so small that practically the mass of the solvent is equal to the mass of the solution. In these cases, a percentage cannot be used as a reference, that is, analyze how many grams of solute there are in 100 units of the solution. Thus, you need to use larger parts of the solution as a reference, like 1000 000 or 106, that is, parts per million (ppm).
The mathematical calculation in ppm is done with the following formula:
1 ppm = 1 part of solute___ |
There are cases where the solution is so diluted that it is necessary to use parts per billion (ppb) or even parts per trillion (ppt). Their formulas are, respectively:
|
1 ppb = 1 part of solute___ Do not stop now... There's more after the advertising ;) |
1 ppt = 1 part of solute_____ |
If the solution is solid or liquid, the concentration in ppm is given by mass; if it is in the gaseous state, it will be supplied in volume.
Thus, if we say that the maximum amount of lead allowed in public water supplies should be of 0.015 ppm, that means there is 0.015 g or 15 mg of lead in 1 million grams of solution, that is, water.
Another important example of the use of the concentration in ppm was the 2002 resolution of the National Council for the Environment (Conama), which established that the The maximum acceptable amount of sulfur in diesel oil should be 50 parts per million (ppm), that is, 50 parts of sulfur for 1,000,000 parts of the oil diesel. Currently, the oil received by metropolitan regions contains 500 ppm; and, in rural areas of the country, this content can reach 2000 ppm.
By Jennifer Fogaça
Graduated in Chemistry
Would you like to reference this text in a school or academic work? Look:
FOGAÇA, Jennifer Rocha Vargas. "Parts per million (ppm)"; Brazil School. Available in: https://brasilescola.uol.com.br/quimica/partes-por-milhao-ppm.htm. Accessed on June 28, 2021.
