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A concentration of an osmatically active substance is said to be hyperosmolar if a high concentration causes a change in osmatic pressure in a tissue, organ, or system. Similarly, it is said to be hypoossmolar if the osmolarity, or osmatic concentration, is too low. For example, if the osmolarity of
432:
A solution can be both hyperosmotic and isotonic. For example, the intracellular fluid and extracellular can be hyperosmotic, but isotonic – if the total concentration of solutes in one compartment is different from that of the other, but one of the ions can cross the membrane (in other words, a
177:(NaCl) dissociates into Na and Cl ions. Thus, for every 1 mole of NaCl in solution, there are 2 osmoles of solute particles (i.e., a 1 mol/L NaCl solution is a 2 osmol/L NaCl solution). Both sodium and chloride ions affect the osmotic pressure of the solution.
519:
According to IUPAC, osmolality is the quotient of the negative natural logarithm of the rational activity of water and the molar mass of water, whereas osmolarity is the product of the osmolality and the mass density of water (also known as osmotic concentration).
406:(isotonic, hypertonic, hypotonic). The terms are related in that they both compare the solute concentrations of two solutions separated by a membrane. The terms are different because osmolarity takes into account the total concentration of penetrating solutes
202:
Multiple compounds may contribute to the osmolarity of a solution. For example, a 3 Osm solution might consist of: 3 moles glucose, or 1.5 moles NaCl, or 1 mole glucose + 1 mole NaCl, or 2 moles glucose + 0.5 mole NaCl, or any other such combination.
302:
421:, causing momentary changes in cell volume as the solutes "pull" water molecules with them. Non-penetrating solutes cannot cross the cell membrane; therefore, the movement of water across the cell membrane (i.e.,
595:
891:"The Effect of Changing Serum Osmolality on the Release of Antidiuretic Hormone in Certain PAtients with Decompensated Cirrhosis of the Liver and Low Serum Osmolality"
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Osmolarity is distinct from molarity because it measures osmoles of solute particles rather than moles of solute. The distinction arises because some compounds can
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633:(vasopressin) is partly responsible for this process by controlling the amount of water the body retains from the kidney when filtering the blood stream.
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840:
Martin's physical pharmacy and pharmaceutical sciences: physical chemical and biopharmaceutical principles in the pharmaceutical sciences
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Nonionic compounds do not dissociate, and form only 1 osmole of solute per 1 mole of solute. For example, a 1 mol/L solution of
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Plasma osmolarity/osmolality is important for keeping proper electrolytic balance in the blood stream. Improper balance can lead to
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of solution (thus the conversion by multiplying with the mass density of solvent in solution (kg solvent/litre solution).
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non-penetrating solutes, whereas tonicity takes into account the total concentration of non-freely penetrating solutes
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The osmolarity of a solution, given in osmoles per liter (osmol/L) is calculated from the following expression:
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is too high, it can cause severe tissue damage. One example of a condition caused by hypoosmolarity is
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of a solution is expressed as "M" (pronounced "molar"). Whereas molarity measures the number of
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penetrating solute), drawing water with it, thus causing no net change in solution volume.
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is the number of particles (e.g. ions) into which a molecule dissociates. For example:
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can also be larger than 1 (e.g. for sucrose). For salts, electrostatic effects cause
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In simpler terms, osmolality is an expression of solute osmotic concentration per
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794:. Preceded by: Costanzo, Linda S., 1947- (Sixth ed.). Philadelphia, PA.
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of a solution and the determination of how the solvent will diffuse across a
843:. Philadelphia, Pennsylvania: Lippincott Williams and Wilkins. p. 158.
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63:(osmol/L or Osm/L). The osmolarity of a solution is usually expressed as
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297:{\displaystyle \mathrm {osmolarity} =\sum _{i}\varphi _{i}\,n_{i}C_{i}}
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per unit volume of solution. This value allows the measurement of the
590:{\displaystyle {\text{osmolality}}=\sum _{i}\varphi _{i}\,n_{i}m_{i}}
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188:), which dissociates into Mg and 2Cl ions. For every 1 mole of MgCl
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of solute that contribute to the osmotic pressure of a solution. A
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is between 0 and 1 where 1 indicates 100% dissociation. However,
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are related but distinct concepts. Thus, the terms ending in
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Scientific
Foundations of Biochemistry in Clinical Practice
716:(2nd ed.). Oxford: Blackwell Scientific Publications.
713:
IUPAC. Compendium of
Chemical Terminology (the "Gold Book")
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to be smaller than 1 even if 100% dissociation occurs (see
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in the solution, there are 3 osmoles of solute particles.
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Widmaier, Eric P.; Hershel Raff; Kevin T. Strang (2008).
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McNaught, A. D.; Wilkinson, A.; Chalk, S. J. (1997).
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30:"Osmolarity" redirects here. Not to be confused with
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Panganiban, Jennifer; Mascarenhas, Maria R. (2021),
169:, can dissociate in solution into their constituent
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496:of the solution in g/ml, which is 1.025 g/ml for
67:(pronounced "osmolar"), in the same way that the
362:represents the identity of a particular solute.
123:unit of measurement that defines the number of
79:of solution, osmolarity measures the number of
864:Shmukler, Michael (2004). Elert, Glenn (ed.).
1026:Online Serum Osmolarity/Osmolality calculator
982:"Psychiatric Disorders of Biochemical Origin"
8:
944:Pediatric Gastrointestinal and Liver Disease
417:Penetrating solutes can diffuse through the
106:sachet with the osmolarity of its components
837:Martin, Alfred N.; Patrick J Sinko (2006).
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822:: CS1 maint: location missing publisher (
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527:of solvent, whereas osmolarity is per
446:Plasma osmolarity, the osmolarity of
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366:Osmolarity can be measured using an
159:in solution, whereas others cannot.
629:or other life-threatening changes.
994:10.1016/b978-0-7506-0167-2.50013-3
952:10.1016/b978-0-323-67293-1.00088-8
761:Vander's Human Physiology, 11th Ed
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790:Costanzo, Linda S. (2017-03-15).
442:Plasma osmolarity vs. osmolality
147:) is 1/1,000,000 of an osmole.
988:, Elsevier, pp. 144–160,
1:
610:is the molality of component
135:) is 1/1,000 of an osmole. A
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81:osmoles of solute particles
51:, defined as the number of
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450:, can be calculated from
376:Freezing-point depression
765:. McGraw-Hill. pp.
390:Osmolarity vs. tonicity
384:Boiling-point elevation
980:Donaldson, D. (1994),
940:"Parenteral Nutrition"
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372:colligative properties
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89:semipermeable membrane
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345:of 1, while NaCl has
329:Debye–Hückel equation
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38:Osmotic concentration
870:The Physics Factbook
644:parenteral nutrition
631:Antidiuretic hormone
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55:(Osm) of solute per
44:, is the measure of
40:, formerly known as
1046:Amount of substance
313:osmotic coefficient
180:Another example is
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866:"Density of blood"
693:Biological Science
680:van 't Hoff factor
648:water intoxication
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182:magnesium chloride
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1003:978-0-7506-0167-2
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907:10.1172/jci103832
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619:dehydration
437:In medicine
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129:milliosmole
1035:Categories
1009:2024-05-10
967:2024-05-10
875:2022-01-23
792:Physiology
729:23 January
686:References
540:osmolality
459:osmolality
374:, such as
358:the index
207:Definition
165:, such as
157:dissociate
42:osmolarity
32:Osmolality
1051:Solutions
818:cite book
810:965761862
623:alkalosis
558:φ
548:∑
513:anhydrous
368:osmometer
265:φ
255:∑
925:13641405
675:Tonicity
665:Molality
660:Molarity
654:See also
627:acidosis
511:is the (
400:-osmotic
396:tonicity
69:molarity
61:solution
494:density
492:is the
480:where:
423:osmosis
339:glucose
311:is the
197:glucose
93:osmosis
59:(L) of
53:osmoles
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767:108–12
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599:where
529:volume
404:-tonic
304:where
117:osmole
77:volume
46:solute
382:, or
349:of 2;
184:(MgCl
167:salts
125:moles
73:moles
65:Osm/L
57:litre
998:ISBN
956:ISBN
921:PMID
845:ISBN
824:link
806:OCLC
796:ISBN
771:ISBN
731:2022
718:ISBN
525:mass
412:only
341:has
171:ions
141:μOsm
133:mOsm
111:Unit
990:doi
948:doi
911:PMC
903:doi
489:sol
467:sol
462:× (
408:and
104:ORS
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