Osmolarity and Osmotic Pressure (van't Hoff)

Osmolarity Osm = i x C counts effective dissolved particles, with the van't Hoff factor i = 1 (glucose, urea), 2 (NaCl, KCl), or 3 (CaCl2, MgCl2, Na2SO4); osmotic pressure Pi = Osm x R x T (R = 0.08206 L*atm/(mol*K), T in kelvin). Physiological saline (0.9% NaCl = 0.154 mol/L, i = 2) is 0.308 Osmol/L (308 mOsm/L) and exerts about 7.8 atm at body temperature - which is why isotonic fluids are formulated near 300 mOsm/L. Ideal dilute-solution form (a real i falls below nominal at high concentration); osmolarity is per liter of solution (osmolality is per kg of solvent). A first-principles chemistry aid; the osmometer reading governs.

Osmolarity Osm = i x C (i the van't Hoff factor: 1 glucose/urea, 2 NaCl/KCl, 3 CaCl2/MgCl2/Na2SO4); osmotic pressure Pi = Osm x R x T, R = 0.08206 L*atm/(mol*K), T in kelvin. mOsm/L = 1000 x Osm.

The van't Hoff colligative-property relations (osmolarity and osmotic pressure); standard physical chemistry. First principles.

van't Hoff's law and the dissociation factors are public first-principles chemistry; the concentration and solute are the user's inputs.

Verify protocol against your lab's SOP before pipetting. A miscalculated dilution can ruin a run or a sample.

Field names used by the API: concentration_mol_l, vant_hoff_i, temperature_c, osmolarity_mosmol_l, osmotic_pressure_atm

• Osmolarity Osm = i x C; i = 1 (glucose/urea), 2 (NaCl/KCl), 3 (CaCl2/MgCl2)van't Hoff colligative properties
• Osmotic pressure Pi = Osm x R x T, R = 0.08206 L*atm/(mol*K), T in kelvinvan't Hoff's law
• Ideal dilute solution the real i falls below nominal at high concentration (an osmotic coefficient corrects it); per liter of solutionscope of this tile