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Principle of a group-contribution method. The Joback method is a group-contribution method.These kinds of methods use basic structural information of a chemical molecule, like a list of simple functional groups, add parameters to these functional groups, and calculate thermophysical and transport properties as a function of the sum of group parameters.
The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid [ 1 ][ 2 ] and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding environmental pressure. A liquid in a partial vacuum, i.e., under a lower pressure, has a lower ...
A sealed capillary, open end pointing down, is placed in the fusion tube. The Thiele tube is heated; dissolved gases evolve from the sample first. Once the sample starts to boil, heating is stopped, and the temperature starts to fall. The temperature at which the liquid sample is sucked into the sealed capillary is the boiling point of the sample.
The Siwoloboff method is used to determine the boiling point of small samples of liquid chemicals. A sample in an ignition tube (also called a fusion tube) is attached to a thermometer with a rubber band, and immersed in a Thiele tube, water bath, or other suitable medium for heating. A sealed capillary, open end pointing down, is placed in the ...
Trouton's rule. In thermodynamics, Trouton's rule states that the (molar) entropy of vaporization is almost the same value, about 85–88 J/ (K·mol), for various kinds of liquids at their boiling points. [1] The entropy of vaporization is defined as the ratio between the enthalpy of vaporization and the boiling temperature.
Through the procedure called ebullioscopy, a known constant can be used to calculate an unknown molar mass. The term ebullioscopy means "boiling measurement" in Latin. This is related to cryoscopy, which determines the same value from the cryoscopic constant (of freezing point depression). This property of elevation of boiling point is a ...
This page contains tables of azeotrope data for various binary and ternary mixtures of solvents. The data include the composition of a mixture by weight (in binary azeotropes, when only one fraction is given, it is the fraction of the second component), the boiling point (b.p.) of a component, the boiling point of a mixture, and the specific gravity of the mixture.
Boiling-point elevation. Boiling-point elevation is the phenomenon whereby the boiling point of a liquid (a solvent) will be higher when another compound is added, meaning that a solution has a higher boiling point than a pure solvent. This happens whenever a non-volatile solute, such as a salt, is added to a pure solvent, such as water.