Low BP azeotropic mixtures show which deviation and why..???
Answers
Answer:
The most common example is the azeotrope between water and ethanol (grain alcohol). Water boils at 100 ºC and ethanol boils at 78.3 ºC. The mixture will boil at 78.2 ºC and have a composition of 95% ethanol and 5% water by volume. This is a binary azeotrope because it involves two components.
Answer:
Explanation:1. Azeotropic mixtures with minimum boiling point: The mixture of two liquids whose boiling Point is less than either of the two pure components. This is formed by that composition of a nonideal solution showing positive deviation for which the vapour pressure is maximum.
An azeotrope (/əˈziːəˌtroʊp/)[1] or a constant boiling point mixture is a mixture of two or more liquids whose proportions cannot be altered or changed by simple distillation.[2] This happens because when an azeotrope is boiled, the vapour has the same proportions of constituents as the unboiled mixture. Because their composition is unchanged by distillation, azeotropes are also called (especially in older texts) constant boiling point mixtures.
Some azeotropic mixtures of pairs of compounds are known,[3] and many azeotropes of three or more compounds are also known.[4] In such a case it is not possible to separate the components by fractional distillation. There are two types of azeotropes: minimum boiling azeotrope and maximum boiling azeotrope. A solution that shows greater positive deviation from Raoult's law forms a minimum boiling azeotrope at a specific composition. For example, an ethanol-water mixture (obtained by fermentation of sugars) on fractional distillation yields a solution containing approximately 95% by volume of ethanol. Once this composition has been achieved, the liquid and vapour have the same composition, and no further separation occurs. A solution that shows large negative deviation from Raoult's law forms a maximum boiling azeotrope at a specific composition. Nitric acid and water is an example of this class of azeotrope. This azeotrope has an approximate composition of 68% nitric acid and 32% water by mass, with a boiling point of 393.5 K (120.4 °C).