antifreeze

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antifreeze,

substance added to a solvent to lower its freezing point. The solution formed is called an antifreeze mixture. Antifreeze is typically added to water in the cooling system of an internal-combustion engine so that it may be cooled below the freezing point of pure water (32°F; or 0°C;) without freezing. Any substance that dissolves will cause freezing-point depression (see colligative propertiescolligative properties,
properties of a solution that depend on the number of solute particles present but not on the chemical properties of the solute. Colligative properties of a solution include freezing point (see freezing), boiling point, osmotic pressure (see osmosis), and
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); a desirable antifreeze also should not corrode metal parts, attack rubber, become viscous at low temperatures, or evaporate readily at the ordinary engine operating temperature. It should be chemically stable, a good conductor of heat, and a poor conductor of electricity. Ethylene glycolglycol
, dihydric alcohol in which the two hydroxyl groups are bonded to different carbon atoms; the general formula for a glycol is (CH2)n(OH)2.
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 is the most widely used automotive cooling-system antifreeze, although methanol, ethanol, isopropyl alcohol, and propylene glycol are also used. Substances that inhibit corrosion are usually added; antifoaming agents are sometimes added as well. In automotive windshield-washer fluids, an alcohol (e.g., methanol) is usually added to keep the mixture from freezing; it also acts as a solvent to help clean the glass. The brine used in some commercial refrigeration systems is an antifreeze mixture; it is typically a water solution of calcium chloride or propylene glycol.

Antifreeze

 

a liquid with a low freezing point, used for cooling internal combustion engines and other equipment operating at temperatures below 0°C. The primary requirements for antifreeze are high heat capacity, thermal conductivity, boiling point, and flash point; low viscosity at low temperatures, small vapor pressure, and as little foaming as possible. In addition, antifreeze must not be very corrosive to the metals from which the cooling system parts are made and must not eat away hose and gasket materials. These requirements are met to a greater or lesser degree by aqueous solutions of ethylene glycol, glycerine, certain alcohols, and other organic compounds as well as by aqueous salt solutions (for instance, calcium chloride).

The best antifreeze materials are aqueous solutions of ethylene glycol with anticorrosion additives to prevent corrosion (such as sodium phosphate). It is possible to obtain mixtures with a freezing point as low as -75°C (66.7 percent ethylene glycol and 33.3 percent water). Upon freezing, such solutions increase in volume insignificantly (0.3 percent with a 55 to 65 percent water content) and when cooled below freezing do not rupture pipes and radiators of the cooling system.

Domestic industry manufactures brands 40 and 65 ethylene glycol antifreeze (freezing points of -40°C and -65°C, respectively) with sodium phosphate and brand 40 M with sodium molybdate.

REFERENCES

Motornye i reaktivnye masía i zhidkosti. Edited by K. K. Papok and E. G. Semenido, 4th ed. Moscow, [1964].
Bobrov, N. N., and P. I. Voropai. Primenenie topliv i smazochnykh materialov, 2nd ed. Moscow, 1968.

V. V. PANOV

antifreeze

[′an·tē‚frēz]
(chemistry)
A substance added to a liquid to lower its freezing point; the principal automotive antifreeze component is ethylene glycol.

antifreeze

a liquid, usually ethylene glycol (ethanediol), added to cooling water to lower its freezing point, esp for use in an internal-combustion engine
References in periodicals archive ?
The latter hypothesis needs to be confirmed with further study, as does the result indicating the improved performance of the antifreeze without the automotive components.
Effect of propylene glycol antifreeze on captures of Mexican fruit flies (Diptera: Tephritidae) in traps baited with biolures and AFF lures.
LOW TOX PROPYLENE GLYCOL ANTIFREEZE AS THE CAPTURE LIQUID.
The researchers differ, however, over how firmly the antifreeze proteins bond to ice surfaces.
DeVries and his colleagues, for example, have looked at the way ice crystals in an antifreeze glycopeptide solution scatter light.
No one yet knows exactly how antifreeze molecules bind to an ice crystal.
Another question concerns the shape of these antifreeze glycopeptides in solution.
When ice does grow, it begins to grow abnormally," says Feeney, who has been working with Hallett and several colleagues and students to document the effects of antifreeze proteins on ice crystal structure.
Instead, long needles grow out from the crystals, even when the antifreeze amounts used are so small that the freezing point isn't lowered significantly.
Moreover, the crystal shape change means that the antifreeze proteins affect some crystal faces more than others.
When an antifreeze solution is supercooled below -5[deg.