Azeotropic solution

Solutions in which intermolecular forces are stronger in the solution than in the pure components have negative deviations from Raoulfs law some form maximum-boiling azeotropes. Solutions in which intermolecular forces are weaker in the solution than in the pure components have positive deviations from Raoulfs law some form minimum-boiling azeotropes. 

For a solution or mixture of two or more distinct liquid components, an azeotrope is that composition (typically measured in mole fractions or percent weight and referred to as the azeotropic solution) with which there is either a maximum point (a negative azeotrope) or a minimum point (a positive azeotrope) in a boiling point versus composition diagram at constant pressure. 

It is well known that nitric acid forms an azeotropic solution with water. It contains 68.5 wt% HNOj and boils at 122 0 under standard atmospheric pressure. 

This rule is very similar to the general law of Wrewsky, as would be expected from the Clausius-Clapeyron equation. The difference between the two rules is that Wrewsky s is based on a knowledge of the latent heats of evaporation of the components from the azeotropic solution, while the present rule is expressed in terms of more readily available quantities, the latent heats of evaporation of the pure liquids. 

Solute Azeotrope Solute y Reference Partition coefficient ... 

An azeotropic mixture of methyl acetate and methanol is a common coproduct from the manufacture of poly(vinyl alcohol) from poly(vinyl acetate) in the presence of methanol and sodium methoxide. The polymerization of vinyl acetate in this azeotropic solution, with the total removal of oxygen from the system, and using conventional free radical initiators is said to afford high-molecular weight poly(vinyl acetate) [106]. 

The reactions proceed with a high yield. In the case of halide derivatives evolved HCl is bound by Py and/or NH3. The transesterification methods are applicable to those cases when the substitution is conducted using an alcohol with a boiling point that is higher than that of the alcohol to be substituted. By this method mixed titanates have also been prepared (Fig. 4-2). The released alcohol can be removed from the reaction mixture either directly during the synthesis or as an azeotropic solution with solvent (most often with benzene). 

The constant boiling mixtures obtained during fractional distillation are called azeotropic solutions. 

The formation of azeotropes, or constant-boiling blends, is known to be a function of the non-ideality of the azeotropic solution, combined with the difference in boiling point between the two pure components. In general, the deviations from ideality can be attributed to contributions from dispersion interactions, dipole/dipole interactions, dipole-induced dipole interactions and hydrogen bonding, this last being one of the most important contributors to azeotrope formation. Ref. 3, Appendix 2 has much more details. 

Water. Hydrogen chloride, a colorless gas with an acrid, irritating odor, is readily soluble in water as the hydrochloric or muriatic acid of commerce. A common concentrated solution is about 36-% HCl and about 12 M. A constant-boiling or azeotropic solution is obtained at 110 °C it contains 20.2- % HCl at 6.1 M. 

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