A liquid blend consists of 30% o-xylene, 60% p-xylene, and 10% m-xylene by weight (w/w). Which statement correctly applies to this mixture ?
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Answer: A. The mixture exhibits an azeotrope at 101.3 kPa
Explanation
Xylene isomers possess very similar physical properties and boiling point ranges. Mixtures of o-xylene, p-xylene, and m-xylene form non-ideal solutions exhibiting azeotropic behavior. At standard atmospheric pressure, this specific liquid blend exhibits azeotropic characteristics. Xylene is an important aromatic hydrocarbon used widely in chemical synthesis and manufacturing. Isomers of xylene have boiling points separated by only a few degrees Celsius. Vapor-liquid equilibrium calculations for close boiling isomers require activity coefficient models.
Distilling close boiling isomer mixtures requires specialized fractional distillation techniques. Petrochemical plants use fractional crystallization alongside distillation to separate xylene isomers. Understanding azeotropic behavior prevents design failures in aromatic separation units. Volume percent does not directly equal weight percent due to differing component densities. Mole percent differs from weight percent because molecular weights of the isomers are identical. Xylene isomers do not exhibit optical isomerism since they lack chiral carbon centers.
- Subject
- Engineering
- Category
- Chemical Engineering
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- —
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- medium
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