antifreezing

Antifreezing refers to substances or formulations that prevent liquids from freezing at subzero temperatures by lowering their freezing point. This is achieved primarily through freezing point depression, where dissolved solutes disrupt the formation of ice crystals in a solvent.

Two broad categories are commonly encountered: antifreeze used in cooling systems and de-icing or winterization fluids. Engine antifreeze is typically a water–glycol mixture, with ethylene glycol or propylene glycol as the main solvent, supplemented by corrosion inhibitors and anti-foam agents. De-icing products used on roads and aircraft usually contain inorganic salts such as calcium chloride or magnesium chloride to melt ice and lower the surface's freezing point.

Common chemicals include ethylene glycol, which is highly effective but toxic if ingested, and propylene glycol, which is less toxic and widely used in consumer products. Modern automotive antifreeze often uses organic acid technology formulations and is designed to be compatible with engine materials. Safe handling and disposal are important due to toxicity and environmental risk.

Limitations include reduced effectiveness at very low temperatures, potential corrosion or material compatibility issues if concentrations are not maintained, and the need to avoid mixing incompatible antifreeze formulations. Fluids should be used and disposed of according to manufacturers' guidelines and local regulations.

See also: antifreeze, de-icer, freezing-point depression, heat transfer fluid.