Condenser (laboratory)
Encyclopedia
Laboratory glassware
Laboratory glassware refers to a variety of equipment, traditionally made of glass, used for scientific experiments and other work in science, especially in chemistry and biology laboratories...
used to cool hot vapors or liquids. A condenser usually consists of a large glass tube
Glass tube
Glass tubes or glass tubing are hollow pieces of borosilicate or flint glass used primarily as laboratory glassware. Glass tubing is commercially available in various thicknesses and lengths. Glass tubing is frequently attached to rubber stoppers....
containing a smaller glass tube running its entire length, within which the hot fluids pass.
The ends of the inner glass tube are usually fitted with ground glass joint
Ground glass joint
Ground glass joints are used in laboratories to quickly and easily fit leak-tight apparatus together from commonly available parts. For example, a round bottom flask, Liebig condenser, and oil bubbler with ground glass joints may be rapidly fitted together to reflux a reaction mixture...
s which are easily fitted with other glassware. During reflux, the upper end is usually left open to the atmosphere or vented through a bubbler or a drying tube
Drying tube
A drying tube or guard tube is a tube-like piece of apparatus used to house a disposable solid desiccant, wherein at one end the tube-like structure terminates in a ground glass joint for use in connecting the drying tube to a reaction vessel, for the purpose of keeping that reaction vessel free of...
to prevent the ingress of water or oxygen.
The outer glass tube usually has two hose connections, and a coolant (usually tap water or chilled water/anti-freeze mixture) is passed through it. For maximum efficiency, and to maintain a smooth and correctly directed thermal gradient so as to minimise the risk of thermal shock to adjacent glassware, the coolant usually (though not necessarily; see 'Allihn condenser - refluxing' below) enters through the lower fitting, and exits through the higher fitting. Maintaining a correct thermal gradient (i.e. entering coolant at the cooler point) is the critical factor. Multiple condensers may be connected in series. Normally a high flow rate is not necessary to maintain a cooling surface.
Applications
Reflux
Reflux is a technique involving the condensation of vapors and the return of this condensate to the system from which it originated. It is used in industrial and laboratory distillations...
, where the hot solvent vapors of a liquid being heated are cooled and allowed to drip back. This reduces the loss of solvent allowing the mixture to be heated for extended periods.
Condensers are used in distillation
Distillation
Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....
to cool the hot vapors, condensing them into liquid for separate collection. For fractional distillation
Fractional distillation
Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate. It is a special type of distillation...
, an air or Vigreux condenser is usually used to slow the rate at which the hot vapors rise, giving a better separation between the different components in the distillate.
For microscale distillation, there are commercially available apparatus which include the "pot", and the condenser fused into one-piece. This reduces the hold-up volume, and obviates the need for ground glass joint
Ground glass joint
Ground glass joints are used in laboratories to quickly and easily fit leak-tight apparatus together from commonly available parts. For example, a round bottom flask, Liebig condenser, and oil bubbler with ground glass joints may be rapidly fitted together to reflux a reaction mixture...
s preventing contamination by grease and air leaks.
Air condenser
An air condenser is the simplest sort of condenser. There is only one tube, and the heat of the fluid is conducted to the glass, which is cooled by air. It is related to the retortRetort
In a chemistry laboratory, a retort is a glassware device used for distillation or dry distillation of substances. It consists of a spherical vessel with a long downward-pointing neck. The liquid to be distilled is placed in the vessel and heated...
used by alchemists
Alchemy
Alchemy is an influential philosophical tradition whose early practitioners’ claims to profound powers were known from antiquity. The defining objectives of alchemy are varied; these include the creation of the fabled philosopher's stone possessing powers including the capability of turning base...
. The air condenser is usually used for fractional distillation
Fractional distillation
Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate. It is a special type of distillation...
and high-temperature condensation, and it can be packed with some material such as glass beads, metal pieces, or Raschig ring
Raschig ring
Raschig rings are pieces of tube used in large numbers as a packed bed within columns for distillations and other chemical engineering processes. They are usually ceramic or metal and provide a large surface area within the volume of the column for interaction between liquid and gas or vapour...
s to increase the number of effective plates.
A standard liebig may often be substituted by actively circulating air rather than a liquid coolant.
Vigreux column
Fractionating column
A fractionating column or fractionation column is an essential item used in the distillation of liquid mixtures so as to separate the mixture into its component parts, or fractions, based on the differences in their volatilities...
for fractional distillation
Fractional distillation
Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate. It is a special type of distillation...
s. Unlike straight-walled columns, a Vigreux column has a series of downward-pointing indentations on the inside wall which serve to dramatically increase the surface area without increasing the length of the condenser. Because of their added complexity, Vigreux columns also tend to be considerably more expensive than traditional straight-walled designs. They are named after Henri Vigreux.
Snyder column
A Snyder column is an extremely effective air-cooled fractionating columnFractionating column
A fractionating column or fractionation column is an essential item used in the distillation of liquid mixtures so as to separate the mixture into its component parts, or fractions, based on the differences in their volatilities...
for fractional distillation
Fractional distillation
Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate. It is a special type of distillation...
s. It contains a number of segments each containing a floating glass ball-valve to enhance vapor-condensate mixing.
Liebig condenser
The Liebig condenser is the most basic water-cooled design. The inner-tube is straight, making it cheaper to manufacture. Though named after the GermanGermany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
chemist
Chemist
A chemist is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties such as density and acidity. Chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms...
Justus Baron von Liebig, he cannot be given credit for having invented it because it had already been in use for some time before him. However, it is believed that he popularized the device.
The true inventors, all of them inventing it independently, were the German chemist Christian Ehrenfried Weigel
Christian Ehrenfried Weigel
Christian Ehrenfried Weigel was a German scientist and, beginning in 1774, a professor of Chemistry, Pharmacy, Botany, and Mineralogy at the University of Greifswald....
in 1771, the French scientist, P. J. Poisonnier in 1779, and the Finnish chemist Johan Gadolin
Johan Gadolin
Johan Gadolin was a Finnish chemist, physicist and mineralogist. Gadolin discovered the chemical element yttrium...
in 1791.
Liebig himself incorrectly attributed the design to the German pharmacist
Pharmacist
Pharmacists are allied health professionals who practice in pharmacy, the field of health sciences focusing on safe and effective medication use...
Johann Friedrich August Gottling
Johann Friedrich August Gottling
Johann Friedrich August Göttling was a notable German chemist. He received his Apothecary degree in 1775 at Langensalza under Johann Christian Wiegleb. Gottling developed and sold chemical assay kits and studied processes for extracting sugar from beets, to supplement his meagre university salary....
who had made improvements to the Weigel design in 1794.
The Liebig condenser is much more efficient than a simple retort
Retort
In a chemistry laboratory, a retort is a glassware device used for distillation or dry distillation of substances. It consists of a spherical vessel with a long downward-pointing neck. The liquid to be distilled is placed in the vessel and heated...
due to its use of liquid for cooling. Water can absorb much more heat than the same volume of air, and its constant circulation through the water jacket keeps the condenser's temperature constant. Therefore, a Liebig condenser can condense a much greater flow of incoming vapour than an air condenser or retort.
Additionally, stainless steel 'wool' or another heat-conductive, nonreactive material can be loosely placed in the inner cylinder of a Liebig condenser, substantially increasing the reflux effect, and the overall efficiency of the distillation. The cooling water should flow from top to bottom in this instance, as that also increases the efficiency and helps prevent thermal shock to the glassware.
West condenser
A variant of the Liebig condenser having a more slender design. The narrower coolant jacket may render more efficient cooling with respect to coolant consumption.Allihn condenser
The Allihn condenser or bulb condenser or simply reflux condenser is named after Felix Richard Allihn.The Allihn condenser consists of a long glass tube with a water jacket
Water jacket
A water jacket is a water-filled void surrounding a device, typically a metal sheath having intake and outlet vents to allow water to be pumped through the void. The flow of water to an external heating or cooling device allows precise temperature control of the device.-Applications:Water jackets...
. A series of large and small constrictions on the inside tube increases the surface area upon which the vapor constituents may condense. Ideally suited for laboratory-scale refluxing.
Again, a liebig readily substitutes, taking care to enter coolant at the cooler point to maintain a correct thermal gradient; i.e., the HIGHER fitting in this case.
Graham condenser
A Graham condenser (also Grahams or Inland Revenue condenser) has a coolant-jacketed spiral coil running the length of the condenser serving as the vapor/condensate path. This is not to be confused with the coil condenser.Coil condenser
A coil condenser is essentially a Graham condenser with an inverted coolant/vapor configuration. It has a spiral coil running the length of the condenser through which coolant flows, and this coolant coil is jacketed by the vapor/condensate path.Dimroth condenser
A Dimroth condenser, named after Otto DimrothOtto Dimroth
Otto Dimroth was a German chemist. He is known for the Dimroth rearrangement, as well as a type of condenser with an internal double spiral, the Dimroth condenser....
, is somewhat similar to the coil condenser. It has an internal double spiral through which coolant flows such that the coolant inlet and outlet are both at the top. The vapors travel through the jacket from bottom to top. Dimroth condensers are more effective than conventional coil condensers. They are often found in rotary evaporator
Rotary evaporator
A rotary evaporator is a device used in chemical laboratories for the efficient and gentle removal of solvents from samples by evaporation...
s.
Friedrichs condenser
A Friedrichs condenser (sometimes incorrectly Friedrich condenser), also known as a spiraled finger condenser, consists of a large, spiraled internal cold fingerCold finger
A cold finger is a piece of laboratory equipment that is used to generate a localized cold surface. It is named for its resemblance to a finger as is a type of cold trap....
-type capillary tube disposed within a wide cylindrical housing. Coolant flows through the internal cold finger; accordingly, vapors rising up through the housing must pass along the spiraled path.
The spiral cold finger-type apparatus now known as the Friedrichs condenser was invented by Fritz Walter Paul Friedrichs
Fritz Walter Paul Friedrichs
Fritz Walter Paul Friedrichs was a German chemist. He invented the spiral cold finger-type condenser, now most commonly known as a Friedrichs condenser, which he described in a 1912 article published in the Journal of the American Chemical Society.-References:...
, who published a design for this type of condenser in 1912.
Other coolants
The above water-cooled condensers can be used with other chilled liquids such as refrigerated ethanolEthanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
which can be thermostatically cooled in a recycling pump unit. Using liquids other than water allows the condenser to cool below the freezing point of water. This is necessary if the fluid to be condensed boils at a temperature below 0 °C (e.g. dimethyl ether
Dimethyl ether
Dimethyl ether , also known as methoxymethane, is the organic compound with the formula . The simplest ether, it is a colourless gas that is a useful precursor to other organic compounds and an aerosol propellant. When combusted, DME produces minimal soot and CO, though HC and NOx formation is...
which boils at −23.6 °C).
Solid dry ice
Dry ice
Dry ice, sometimes referred to as "Cardice" or as "card ice" , is the solid form of carbon dioxide. It is used primarily as a cooling agent. Its advantages include lower temperature than that of water ice and not leaving any residue...
or an acetone
Acetone
Acetone is the organic compound with the formula 2CO, a colorless, mobile, flammable liquid, the simplest example of the ketones.Acetone is miscible with water and serves as an important solvent in its own right, typically as the solvent of choice for cleaning purposes in the laboratory...
/dry ice
Dry ice
Dry ice, sometimes referred to as "Cardice" or as "card ice" , is the solid form of carbon dioxide. It is used primarily as a cooling agent. Its advantages include lower temperature than that of water ice and not leaving any residue...
mixture can be used in a cold finger
Cold finger
A cold finger is a piece of laboratory equipment that is used to generate a localized cold surface. It is named for its resemblance to a finger as is a type of cold trap....
as a coolant. As with other alternative coolants, these permit cooling below 0 °C.