What does wt ppm mean?

Question

I think ppm means 'parts per million'
But does the 'wt' stand for (example 500 wt ppm of water)

Answer 1

You've answered your own question.

ppm is parts per million.

wt is weight.

ppm is a measure of a ratio or concentration, common in chemistry and geochemistry. The ratio can be based on volume, weight, moles, numbers, or other specified parameters and in your case wt ppm means parts per million by weight. Scientists use ppm just like a percentage to measure low concentrations.

In your example, 500 wt ppm means there are 500 parts per 999,500 parts, and they are based on a weight ratio. Another way to look at is that the concentration is 0.05% by weight. The "weight" versus "volume" is not significant if the specific gravity of the two elements or compounds or whetever are similar, but if they are different it is important to specify if the reference is volume or weight.

Answer 2

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There is no such thing as "volume ppm", ppm is defined as mircrograms of solute per gram of solution. In other words, an aqueous solution that is 3 ppm in hydrochoric acid has 3 micrograms of HCl in a portion of solution that weighs 1 gram. I'm not sure what you mean by "dosage"... dosage is a term used in medicine but not generally in chemistry. If you want a solution to be a certain concentration of HCl, it is better to start with the more concentrated HCl that you have access to and use M1V1 = M2V2 to dilute it to a lower concentration. You cannot weigh out the concentrated HCl and use the ppm system, because the concentrated HCl (that you say has a specific gravity of 1.34) is not pure HCl, it is already a solution in water.

Answer 3

Abbreviation for the expression of concentration, parts-per-million. For solid and liquid concentrations, ppm is stated in weight (mass) units. For example: (1) Calcite in a ground barite sample is 400 ppm. (2) Calcium chloride in a water solution is 250,000 ppm. Note that the relationship of ppm to weight percentage is 10,000 ppm = 1 wt.%. For gases, ppm is in volume (or mole) units. For example, H2S in an air sample is 10 ppm (both by volume or by moles).

Answer 4

Only a guess, but wt probably means weight.
500 ppm by weight is different from 500 ppm by volume.

Answer 5

ppm stands for parts per million. It is a common unit of concentration of gases or vapour in air