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  2. Parts-per notation - Wikipedia

    en.wikipedia.org/wiki/Parts-per_notation

    In fractions like "2 nanometers per meter" (2 n m / m = 2 nano = 2×10 −9 = 2 ppb = 2 × 0.000 000 001), so the quotients are pure-number coefficients with positive values less than or equal to 1. When parts-per notations, including the percent symbol (%), are used in regular prose (as opposed to mathematical expressions), they are still pure ...

  3. Total dissolved solids - Wikipedia

    en.wikipedia.org/wiki/Total_dissolved_solids

    When measuring water treated with water softeners, high levels of total dissolved solids do not correlate to hard water, as water softeners do not reduce TDS; rather, they replace magnesium and calcium ions, which cause hard water, with an equal charge of sodium or potassium ions, e.g. Ca 2+ ⇌ 2 Na +, leaving overall TDS unchanged [9] or even ...

  4. Immediately dangerous to life or health - Wikipedia

    en.wikipedia.org/wiki/Immediately_dangerous_to...

    1000 ppm: 79243: 10102-44-0: 0930: Nitrogen dioxide: 37.6 mg/m 3: 20 ppm: 10102440: 7783-54-2: 1234: Nitrogen trifluoride: 2900 mg/m 3: 2000 ppm: 7783542: 55-63-0: 0186: Nitroglycerine: 75 mg/m 3-55630: 75-52-5: 0522: Nitromethane: 1875 mg/m 3: 750 ppm: 75525: 108-03-2: 1050: 1-Nitropropane: 3640 mg/m 3: 1000 ppm: 108032: 79-46-9: 0187: 2 ...

  5. Hard water - Wikipedia

    en.wikipedia.org/wiki/Hard_water

    Parts per million (ppm) is usually defined as 1 mg/L CaCO 3 (the definition used below). [20] It is equivalent to mg/L without chemical compound specified, and to American degree . Grain per gallon (gpg) is defined as 1 grain (64.8 mg) of calcium carbonate per U.S. gallon (3.79 litres), or 17.118 ppm.

  6. Useful conversions and formulas for air dispersion modeling

    en.wikipedia.org/wiki/Useful_conversions_and...

    1 percent by volume = 10,000 ppmv (i.e., parts per million by volume). Care must be taken with the concentrations expressed as ppbv to differentiate between the British billion which is 10 12 and the USA billion which is 10 9.

  7. Conductivity (electrolytic) - Wikipedia

    en.wikipedia.org/wiki/Conductivity_(electrolytic)

    While this is an error, it can often be assumed to be equal to the traditional μS/cm. Often, by typographic limitations μS/cm is expressed as uS/cm. The conversion of conductivity (in μS/cm) to the total dissolved solids (in mg/kg) depends on the chemical composition of the sample and can vary between 0.54 and 0.96.

  8. Equivalent weight - Wikipedia

    en.wikipedia.org/wiki/Equivalent_weight

    For example, 50 g of zinc will react with oxygen to produce 62.24 g of zinc oxide, implying that the zinc has reacted with 12.24 g of oxygen (from the Law of conservation of mass): the equivalent weight of zinc is the mass which will react with eight grams of oxygen, hence 50 g × 8 g/12.24 g = 32.7 g.

  9. Iron-oxidizing bacteria - Wikipedia

    en.wikipedia.org/wiki/Iron-oxidizing_bacteria

    The anoxygenic phototrophic iron oxidation was the first anaerobic metabolism to be described within the iron anaerobic oxidation metabolism. The photoferrotrophic bacteria use Fe 2+ as electron donor and the energy from light to assimilate CO 2 into biomass through the Calvin Benson-Bassam cycle (or rTCA cycle) in a neutrophilic environment (pH 5.5-7.2), producing Fe 3+ oxides as a waste ...