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  2. Parts-per notation - Wikipedia

    en.wikipedia.org/wiki/Parts-per_notation

    At 10 000 ppm the solution is a deep red colour. As the concentration decreases the colour becomes orange, then a vibrant yellow, with the final 1 ppm sample a very pale yellow. In science and engineering , the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities , e.g. mole fraction or ...

  3. CRC Standard Mathematical Tables - Wikipedia

    en.wikipedia.org/wiki/CRC_Standard_Mathematical...

    CRC Standard Mathematical Tables (also CRC Standard Mathematical Tables and Formulas or SMTF) is a comprehensive one-volume handbook containing a fundamental working knowledge of mathematics and tables of formulas.

  4. Total dissolved solids - Wikipedia

    en.wikipedia.org/wiki/Total_dissolved_solids

    where TDS is expressed in mg/L and EC is the electrical conductivity in microsiemens per centimeter at 25 °C. The conversion factor k e varies between 0.55 and 0.8. [5] Some TDS meters use an electrical conductivity measurement to the ppm using the above formula. Regarding units, 1 ppm indicates 1 mg of dissolved solids per 1,000 g of water. [6]

  5. List of highly toxic gases - Wikipedia

    en.wikipedia.org/wiki/List_of_highly_toxic_gases

    Toxic: a chemical that has a median lethal concentration (LC 50) in air of more than 200 parts per million (ppm) but not more than 2,000 parts per million by volume of gas or vapor, or more than 2 milligrams per liter but not more than 20 milligrams per liter of mist, fume or dust, when administered by continuous inhalation for 1 hour (or less if death occurs within 1 hour) to albino rats ...

  6. Triethylamine - Wikipedia

    en.wikipedia.org/wiki/Triethylamine

    Triethylamine is the chemical compound with the formula N(CH 2 CH 3) 3, commonly abbreviated Et 3 N. Like triethanolamine and tetraethylammonium , it is often abbreviated TEA. [ 8 ] [ 9 ] It is a colourless volatile liquid with a strong fishy odor reminiscent of ammonia .

  7. Hoagland solution - Wikipedia

    en.wikipedia.org/wiki/Hoagland_solution

    The main difference between solution (1) and solution (2) is the different use of nitrate-nitrogen and ammonium-nitrogen based stock solutions to prepare the respective Hoagland solution of interest. Accordingly, the original 1933 and the modified concentrations of 1938 and 1950 for each essential element and sodium are shown below, the ...

  8. Molar concentration - Wikipedia

    en.wikipedia.org/wiki/Molar_concentration

    Molar concentration or molarity is most commonly expressed in units of moles of solute per litre of solution. [1] For use in broader applications, it is defined as amount of substance of solute per unit volume of solution, or per unit volume available to the species, represented by lowercase : [2]

  9. Clarke number - Wikipedia

    en.wikipedia.org/wiki/Clarke_number

    If the concentration of a commodity in an ore X is [ppm], and the "clarke" of that commodity is [ppm], then "the clarke of concentration" of that commodity X is = (dimensionless). The value represents the degree to which the commodity is concentrated from crustal abundances to the ore by natural geochemical processes; a clue for whether the ...