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At atmospheric pressure, mixtures of ethanol and water form an azeotrope at about 89.4 mol% ethanol (95.6% ethanol by mass, [83] 97% alcohol by volume), with a boiling point of 351.3 K (78.1 °C). [84] At lower pressure, the composition of the ethanol-water azeotrope shifts to more ethanol-rich mixtures. [85]
8 Boiling points of aqueous solutions. 9 Charts. 10 References. Toggle the table of contents. ... Excess volume of the mixture of ethanol and water (volume contraction)
Boiling point (°C) K b (°C⋅kg/mol) Freezing point (°C) ... Ethanol: 0.78 78.4 1.22 –114.6 –1.99 ... Water: 100.00 0.512 0.00
This page contains tables of azeotrope data for various binary and ternary mixtures of solvents. The data include the composition of a mixture by weight (in binary azeotropes, when only one fraction is given, it is the fraction of the second component), the boiling point (b.p.) of a component, the boiling point of a mixture, and the specific gravity of the mixture.
Owing to the presence of the polar OH alcohols are more water-soluble than simple hydrocarbons. Methanol, ethanol, and propanol are miscible in water. 1-Butanol, with a four-carbon chain, is moderately soluble. Because of hydrogen bonding, alcohols tend to have higher boiling points than comparable hydrocarbons and ethers.
A well-known example of a positive azeotrope is an ethanol–water mixture (obtained by fermentation of sugars) consisting of 95.63% ethanol and 4.37% water (by mass), which boils at 78.2 °C. [10] Ethanol boils at 78.4 °C, water boils at 100 °C, but the azeotrope boils at 78.2 °C, which is lower than either of its constituents. [ 11 ]
Ethanol-filled thermometer are used in preference to mercury for meteorological measurements of minimum temperatures and can be used down to −70 °C (−94 °F). [2] The physical limitation of the ability of a thermometer to measure low temperature is the freezing point of the liquid used. Ethanol freezes at −114.9 °C (−174.82 °F).
A mixture of constant composition does not have multiple boiling points. An implication of one boiling point is that lighter components never cleanly "boil first". At boiling point, all volatile components boil, but for a component, its percentage in the vapor is the same as its percentage of the total vapor pressure.