PPM is an abbreviation for concentration by mass, expressed in "parts per million," where "parts" refers to a mass of a material. For example, if a laboratory assay (analysis) reports 1 ppm acetic acid, it means that 1 gram of the analyzed solution contains 1 millionth of a gram (1 microgram, or 1 mcg) of acetic acid. This is equivalent to saying 1 kilogram of the solution contains 1 milligram of acetic acid. Concentration is commonly expressed in ppm when samples of air or water to be analyzed contain very small amounts of another substance.
Instructions
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1
Assume that 250 g (grams) of a water sample contains 0.00450 g of acetic acid. Calculate the concentration of acetic acid expressed in ppm.
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2
Divide the mass of acetic acid by the mass of the water sample, as follows: 0.00450 g of acetic acid/250.00 g of water sample = 0.000018 g acetic acid/g water sample.
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3
Multiply the answer found in Step 2 by the factor 1 million to convert the answer to ppm, as follows: 0.000018 g acetic acid/g water sample x 1,000,0000 mcg/g = 18 mcg acetic acid/g water sample = 18 ppm acetic acid.