physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

, an ebullioscope () is an instrument for measuring the

boiling point The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding envi ...

of a

liquid Liquid is a state of matter with a definite volume but no fixed shape. Liquids adapt to the shape of their container and are nearly incompressible, maintaining their volume even under pressure. The density of a liquid is usually close to th ...

. This can be used for determining the alcoholic strength of a mixture, or for determining the

molecular weight A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemi ...

of a non-volatile

solute In chemistry, a solution is defined by IUPAC as "A liquid or solid phase containing more than one substance, when for convenience one (or more) substance, which is called the solvent, is treated differently from the other substances, which are ...

based on the

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 (chemistry), solution has a higher boiling point than a pure solvent. This happens wh ...

. The procedure is known as ebullioscopy. The first ebullioscope was invented in 1838 by Honoré Brossard-Vidal, and was used for measuring alcoholic content. The advantage of this method was that the boiling point is relatively insensitive to other components such as

sugars Sugar is the generic name for Sweetness, sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides ...

. Older alcoholimeters were based on measuring the

density Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...

, which is more sensitive to the presence of other solutes. A famous ebullioscope variant was built by Pierre Marie Edouard Malligand, patented in 1876. The device is used by winemakers still to this day to measure the alcohol contents of wines, using the "Malligand degree" (M°) as a unit of measure.{{Citation needed, date=September 2022 A later version was built by the French chemist François-Marie Raoult, but the difficulty of determining the exact temperature was overcome by the invention of the

Beckmann thermometer A Beckmann thermometer is a device used to measure small differences of temperature, but not absolute temperature values. It was invented by Ernst Otto Beckmann (1853 – 1923), a German chemist, for his measurements of colligative propertie ...

Ernst Otto Beckmann Ernst Otto Beckmann (July 4, 1853 – July 12, 1923) was a German pharmacist and chemist who is remembered for his invention of the Beckmann differential thermometer and for his discovery of the Beckmann rearrangement. Scientific work Ernst Ot ...

in 1887.Ernst Beckmann (1888
"Über die Methode der Molekulargewichtsbestimmung durch Gefrierpunkterneidrigung"
(On the method for the determination of molecular weights by freezing point depression), ''Zeitschrift der Physikalische Chemie'', 2 : 638-715; see especially p. 644. This improvement made the ebullioscope a standard apparatus to determine the

of substances in solution by using the

ebullioscopic constant In thermodynamics, the ebullioscopic constant relates molality to boiling point elevation. It is the ratio of the latter to the former: :\Delta T_\text = iK_\text b * is the van 't Hoff factor, the number of particles the solute splits into ...

of the solvent.

References

Laboratory equipment

See also

References