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A membrane osmometer is a device used to indirectly measure the number average molecular weight () of a polymer sample. One chamber contains pure solvent and the other chamber contains a solution in which the solute is a polymer with an unknown . The osmotic pressure of the solvent across the semipermeable membrane is measured by the membrane osmometer. This osmotic pressure measurement is used to calculate for the sample. == Basic operation == A low concentration solution is created by adding a small amount of polymer to a solvent. This solution is separated from pure solvent by a semipermeable membrane. Solute cannot cross the semipermeable membrane but the solvent is able to cross the membrane. Solvent flows across the membrane to dilute the solution. The pressure required to stop the flow across the membrane is called the osmotic pressure.〔 The osmotic pressure is measured and used to calculate . In an ideally dilute solution, van ‘t Hoff’s law of osmotic pressure can be used to calculate from osmotic pressure.〔 : , number average molecular weight, mass/mole , gas constant , absolute temperature, typically Kelvin , concentration of polymer, mass/volume , osmotic pressure 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Membrane osmometer」の詳細全文を読む スポンサード リンク
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