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Osmotic concentration, formerly known as osmolarity, [1] is the measure of solute concentration, defined as the number of osmoles (Osm) of solute per litre (L) of solution (osmol/L or Osm/L). The osmolarity of a solution is usually expressed as Osm/L (pronounced "osmolar"), in the same way that the molarity of a solution is expressed as "M ...
The laboratory value measures the freezing point depression, properly called osmolality while the calculated value is given in units of osmolarity. Even though these values are presented in different units, when there is a small amount of solute compared to total volume of solution, the absolute values of osmolality vs. osmolarity are very close.
For liquid solutions, the osmotic coefficient is often used to calculate the salt activity coefficient from the solvent activity, or vice versa. For example, freezing point depression measurements, or measurements of deviations from ideality for other colligative properties, allows calculation of the salt activity coefficient through the osmotic coefficient.
The approach is used in determining the colloidal aspects of solutions. [7] In the present day, the method is applied, among other areas, in measuring osmolarity in lens care solutions as well as eye drops. [8] It is further used in clinical chemistry, pharmaceutical, and quality control laboratories, where it facilitates different processes ...
The osmol gap is typically calculated with the following formula (all values in mmol/L): = = ([+] + [] + []) In non-SI laboratory units: Calculated osmolality = 2 x [Na mmol/L] + [glucose mg/dL] / 18 + [BUN mg/dL] / 2.8 + [ethanol/3.7] [3] (note: the values 18 and 2.8 convert mg/dL into mmol/L; the molecular weight of ethanol is 46, but empiric data shows that it does not act as an ideal ...
A hypertonic solution has a greater concentration of non-permeating solutes than another solution. [2] In biology, the tonicity of a solution usually refers to its solute concentration relative to that of another solution on the opposite side of a cell membrane ; a solution outside of a cell is called hypertonic if it has a greater ...
for calculating the density of an NaCl solution at 22°C, with which I get 1.004 , not 1.009, for 0.9% saline at 22°C. Bøyum is the person behind Ficoll separation of lymphocytes [1] and other cell separation techniques, such as Nycodenz [2] for monocyttes, and thus a person unlikely to get this wrong.
Ion pairing occurs to some extent in all electrolyte solutions. This causes the measured van 't Hoff factor to be less than that predicted in an ideal solution. The deviation for the van 't Hoff factor tends to be greatest where the ions have multiple charges. The factor binds osmolarity to molarity and osmolality to molality.