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With the formula below, freezing-point depression can be used to measure the degree of dissociation or the molar mass of the solute. This kind of measurement is called cryoscopy ( Greek cryo = cold, scopos = observe; "observe the cold" [ 7 ] ) and relies on exact measurement of the freezing point.
The freezing point depression osmometer is an osmometer that is used in determining a solution's osmotic concentration as its osmotically active aspects depress its freezing point. In the past, freezing point osmometry has been used to assess the osmotic strength of colloids and solutions. The osmometer uses the solution's freezing point ...
The difference in units is attributed to the difference in the way that blood solutes are measured in the laboratory versus the way they are calculated. 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 ...
Through cryoscopy, a known constant can be used to calculate an unknown molar mass. The term "cryoscopy" means "freezing measurement" in Greek. Freezing point depression is a colligative property, so ΔT depends only on the number of solute particles dissolved
Freezing point (°C) K f (°C⋅kg/mol) Data source; Aniline: 184.3 3.69 –5.96 –5.87 K b & K f [1] ... Freezing-point depression; Boiling-point elevation; References
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.
From this measurement, the clinician can calculate the plasma osmolality of a patient's blood. A second vial is also sent to the laboratory. This vial is put in an instrument that measures the freezing point depression of all the solutes in the plasma. This measurement gives the true plasma osmolality.
An osmometer is a device for measuring the osmotic strength of a solution, colloid, or compound.. There are several different techniques employed in osmometry: Freezing point depression osmometers may also be used to determine the osmotic strength of a solution, as osmotically active compounds depress the freezing point of a solution.