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For example, in the 1930s Widmark measured alcohol and blood by mass, and thus reported his concentrations in units of g/kg or mg/g, weight alcohol per weight blood. Blood is denser than water and 1 mL of blood has a mass of approximately 1.055 grams, thus a mass-volume BAC of 1 g/L corresponds to a mass-mass BAC of 0.948 mg/g.
Change in volume with increasing alc/vol. Mixing two solutions of alcohol of different strengths usually causes a change in volume. Mixing pure water with a solution less than 24% by mass causes a slight increase in total volume, whereas the mixing of two solutions above 24% causes a decrease in volume.
A parametric value in this context is most commonly the concentration of a substance, e.g. 30 mg/L of iron. It may also be a count such as 500 E. coli per litre or a statistical value such as the average concentration of copper is 2 mg/L.
The World Health Organization (WHO) recommends fluoride levels of 0.5–1.5 mg/L, depending on climate and other factors. [5] In the U.S., the guideline was proposed at 0.7 mg/L in 2011 (replacing 0.7–1.2 mg/L) and finalized in 2015. [6] [7] Bottled water often has unknown fluoride levels. [8] Tooth decay affects 60–90% of schoolchildren ...
Referring to a common salt of fluoride, sodium fluoride (NaF), the lethal dose for most adult humans is estimated at 5 to 10 g (which is equivalent to 32 to 64 mg elemental fluoride/kg body weight). [ 2 ] [ 3 ] [ 4 ] Ingestion of fluoride can produce gastrointestinal discomfort at doses at least 15 to 20 times lower (0.2–0.3 mg/kg or 10 to 15 ...
A river or lake water with a salinity of around 70 mg/L will typically have a specific conductivity at 25 °C of between 80 and 130 μS/cm. The actual ratio depends on the ions present. [ 14 ] The actual conductivity usually changes by about 2% per degree Celsius, so the measured conductivity at 5 °C might only be in the range of 50–80 μS/cm.
At 100 °C (212 °F; 373 K), saturated sodium chloride brine is about 28% salt by weight. At 0 °C (32 °F; 273 K), brine can only hold about 26% salt. [ 3 ] At 20 °C one liter of water can dissolve about 357 grams of salt, a concentration of 26.3%.
One part per hundred is generally represented by the percent sign (%) and denotes one part per 100 (10 2) parts, and a value of 10 −2. This is equivalent to about fourteen minutes out of one day. One part per thousand should generally be spelled out in full and not as "ppt" (which is usually understood to represent "parts per trillion").