Azeotropic Distillation

Azeotropic distillation is a separation technique used in chemical engineering to separate azeotropic mixtures. Azeotropes are mixtures of liquids that have a constant boiling point and composition. In other words, the vapor produced during the boiling process has the same composition as the liquid mixture. This makes it difficult to separate the components of the azeotropic mixture using simple distillation methods.

Heat and Volatility in Azeotropic Distillation

- Heat: In azeotropic distillation, heat is applied to the mixture to vaporize the components. This causes the more volatile component to vaporize and rise up the distillation column, while the less volatile component remains in the liquid phase. The heat input required for azeotropic distillation is typically higher than that for simple distillation due to the presence of azeotropes.

- Volatility: Volatility refers to the tendency of a substance to vaporize. In azeotropic distillation, the more volatile component of the mixture vaporizes at a lower temperature compared to the less volatile component. This difference in volatility allows for the separation of the components in the distillation column.

Relative Volatility in Azeotropic Distillation

- Relative Volatility: Relative volatility is a measure of the difference in volatility between the components of a mixture. It is defined as the ratio of the vapor pressures of the more volatile component to the less volatile component at a given temperature. In azeotropic distillation, the relative volatility plays a crucial role in determining the efficiency of separation.

- Role of Relative Volatility: In azeotropic distillation, the relative volatility should be high to achieve effective separation. A high relative volatility indicates a significant difference in vapor pressures between the components, allowing for easier separation. Conversely, a low relative volatility indicates a smaller difference in vapor pressures, making separation more challenging.

Conclusion

In azeotropic distillation, the relative volatility remains low. This implies that the difference in vapor pressures between the components of the azeotropic mixture is small. As a result, achieving effective separation becomes more difficult. Therefore, the correct answer is option 'C' - Relative volatility remains low in azeotropic distillation.