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In solutions, mass concentration is commonly encountered as the ratio of mass/[volume solution], or m/v. In water solutions containing relatively small quantities of dissolved solute (as in biology), such figures may be "percentivized" by multiplying by 100 a ratio of grams solute per mL solution. The result is given as "mass/volume percentage".
It is the same concept as volume percent (vol%) except that the latter is expressed with a denominator of 100, e.g., 18%. The volume fraction coincides with the volume concentration in ideal solutions where the volumes of the constituents are additive (the volume of the solution is equal to the sum of the volumes of its ingredients).
This improper name persists, especially in elementary textbooks. In biology, the unit "%" is sometimes (incorrectly) used to denote mass concentration, also called mass/volume percentage. A solution with 1 g of solute dissolved in a final volume of 100 mL of solution would be labeled as "1%" or "1% m/v" (mass/volume). This is incorrect because ...
The final mass concentration ρ(NaCl) is ρ(NaCl) = 11.6 g / 11.6 g + 100 g = 0.104 g/g = 10.4 %. The volume of such a solution is 104.3mL (volume is directly observable); its density is calculated to be 1.07 (111.6g/104.3mL) The molar concentration of NaCl in the solution is therefore
The volume concentration (not to be confused with volume fraction [3]) is defined as the volume of a constituent divided by the volume of the mixture : =. Being dimensionless, it is expressed as a number, e.g., 0.18 or 18%.
Percentage solution may refer to: Mass fraction (or "% w/w" or "wt.%"), for percent mass; Volume fraction (or "% v/v" or "vol.%"), volume concentration, for percent volume "Mass/volume percentage" (or "% m/v") in biology, for mass per unit volume; incorrectly used to denote mass concentration (chemistry). See usage in biology
For example, the conversion factor between a mass fraction of 1 ppb and a mole fraction of 1 ppb is about 4.7 for the greenhouse gas CFC-11 in air (Molar mass of CFC-11 / Mean molar mass of air = 137.368 / 28.97 = 4.74). For volume fraction, the suffix "V" or "v" is sometimes appended to the parts-per notation (e.g. ppmV, ppbv, pptv).
The pure precipitate is cooled, then measured by weighing, and the difference in weights before and after reveals the mass of analyte lost, in this case calcium oxide. [4] [5] That number can then be used to calculate the amount, or the percent concentration, of it in the original mix. [2] [4] [5]