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Ethanol-water mixtures have less volume than the sum of their individual components at the given fractions. Mixing equal volumes of ethanol and water results in only 1.92 volumes of mixture. [75] [80] Mixing ethanol and water is exothermic, with up to 777 J/mol [81] being released at 298 K. Hydrogen bonding in solid ethanol at −186 °C
Solid–liquid phase change of ethanol–water mixtures. Sodium chloride and water form a eutectic mixture whose eutectic point is −21.2 °C [8] and 23.3% salt by mass. [9] The eutectic nature of salt and water is exploited when salt is spread on roads to aid snow removal, or mixed with ice to produce low temperatures (for example, in ...
This process, known as distillation, separates the ethanol, but its purity is limited to 95–96% due to the formation of a low-boiling water-ethanol azeotrope with maximum (95.6% m/m (96.5% v/v) ethanol and 4.4% m/m (3.5% v/v) water). This mixture is called hydrous ethanol and can be used as a fuel alone, but unlike anhydrous ethanol, hydrous ...
Excess volume of the mixture of ethanol and water (volume contraction) Heat of mixing of the mixture of ethanol and water Vapor–liquid equilibrium of the mixture of ethanol and water (including azeotrope) Solid–liquid equilibrium of the mixture of ethanol and water (including eutecticum) Miscibility gap in the mixture of dodecane and ethanol
Some mixtures form azeotropes, where the mixture boils at a lower temperature than either component. In this example, a mixture of 96% ethanol and 4% water boils at 78.2 °C (172.8 °F); the mixture is more volatile than pure ethanol. For this reason, ethanol cannot be completely purified by direct fractional distillation of ethanol–water ...
Many water injection systems use a mixture of water and alcohol (often close to 50/50), with trace amounts of water-soluble oil. The water provides the primary cooling effect due to its great density and high heat absorption properties. The alcohol is combustible, and also serves as an antifreeze for the water.
Water and ethanol always have negative excess volumes when mixed, indicating the partial molar volume of each component is less when mixed than its molar volume when pure. The partial molar volume is broadly understood as the contribution that a component of a mixture makes to the overall volume of the solution. However, there is more to it ...
Some low molecular weight alcohols of industrial importance are produced by the addition of water to alkenes. Ethanol, isopropanol, 2-butanol, and tert-butanol are produced by this general method. Two implementations are employed, the direct and indirect methods.