Which of the following binary mixtures will have the same composition in liquid and vapour phase?
Which of the following binary mixtures will have the same composition in liquid and vapour phase?
The correct option is D Water - Ethanol
Understanding the concept of same composition in liquid and vapour phase.
Azeotropes are non-ideal binary mixtures of liquids having the same composition in liquid and vapour phase and boil at a constant temperature.
In such cases, it is not possible to separate the components by fractional distillation.
Analysing the options
(A)
Benzene-toluene mixture forms an ideal solution, and an ideal solution does not form azeotropes.
(B)
The solutions that show large negative deviation from Raoult’s law form maximum boiling azeotropes at a specific composition. Nitric acid-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 393.5K.
(C)
The solutions that show a large positive deviation from Raoult’s law at a specific composition form minimum boiling azeotropes. Ethanol-water mixture (obtained by the fermentation of sugars) on fractional distillation gives a solution containing approximately 95% by volume of ethanol. Once this composition, known as azeotrope composition, has been achieved, the liquid and vapour have the same composition, and no further separation occurs.
(D)
n-hexane-n-heptane mixture forms an ideal solution, and an ideal solution does not form azeotropes.
Hence, options (B) and (C) are the correct answers.
Water - Ethanol
Understanding the concept of same composition in liquid and vapour phase.
Azeotropes are non-ideal binary mixtures of liquids having the same composition in liquid and vapour phase and boil at a constant temperature.
In such cases, it is not possible to separate the components by fractional distillation.
Analysing the options
(A)
Benzene-toluene mixture forms an ideal solution, and an ideal solution does not form azeotropes.
(B)
The solutions that show large negative deviation from Raoult’s law form maximum boiling azeotropes at a specific composition. Nitric acid-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 393.5K.
(C)
The solutions that show a large positive deviation from Raoult’s law at a specific composition form minimum boiling azeotropes. Ethanol-water mixture (obtained by the fermentation of sugars) on fractional distillation gives a solution containing approximately 95% by volume of ethanol. Once this composition, known as azeotrope composition, has been achieved, the liquid and vapour have the same composition, and no further separation occurs.
(D)
n-hexane-n-heptane mixture forms an ideal solution, and an ideal solution does not form azeotropes.
Hence, options (B) and (C) are the correct answers.
