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The word colligative is derived from the Latin colligatus meaning bound together. [3] This indicates that all colligative properties have a common feature, namely that they are related only to the number of solute molecules relative to the number of solvent molecules and not to the nature of the solute. [4] Colligative properties include:
All of the colligative properties result from a lowering of the chemical potential of the solvent in the presence of a solute. This lowering is an entropy effect. The greater randomness of the solution (as compared to the pure solvent) acts in opposition to freezing, so that a lower temperature must be reached, over a broader range, before ...
The van 't Hoff factor i (named after Dutch chemist Jacobus Henricus van 't Hoff) is a measure of the effect of a solute on colligative properties such as osmotic pressure, relative lowering in vapor pressure, boiling-point elevation and freezing-point depression.
The boiling point elevation is a colligative property, which means that boiling point elevation is dependent on the number of dissolved particles but not their identity. [1] It is an effect of the dilution of the solvent in the presence of a solute. It is a phenomenon that happens for all solutes in all solutions, even in ideal solutions, and ...
Freezing point depression is a colligative property, so ΔT depends only on the number of solute particles dissolved, not the nature of those particles. Cryoscopy is related to ebullioscopy , which determines the same value from the ebullioscopic constant (of boiling point elevation ).
For example: glucose has n of 1, while NaCl has n of 2; C is the molar concentration of the solute; the index i represents the identity of a particular solute. Osmolarity can be measured using an osmometer which measures colligative properties, such as Freezing-point depression, Vapor pressure, or Boiling-point elevation.
The proportionality to concentration means that osmotic pressure is a colligative property. Note the similarity of this formula to the ideal gas law in the form = = where n is the total number of moles of gas molecules in the volume V, and n/V is the molar concentration of gas molecules.
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.