Elimination of Azeotropic Composition by Changing Pressure

Azeotropic composition is a mixture of two or more components that has a constant boiling point and composition. It is difficult to separate the components of an azeotropic mixture by simple distillation because the vapor produced during boiling has the same composition as the liquid mixture. However, azeotropic composition can be eliminated by changing the pressure of the system. This is because the boiling point of a liquid is dependent on the pressure of the system.

Explanation

When a liquid is heated, it starts to vaporize and the vapor pressure increases. At a certain temperature, the vapor pressure of the liquid becomes equal to the pressure of the surrounding environment. This temperature is called the boiling point of the liquid. For a pure substance, the boiling point is constant at a given pressure.

However, for a mixture of two or more components, the boiling point is not constant. The vapor produced during boiling has a different composition than the liquid mixture. In some cases, the vapor composition may be the same as the liquid composition, leading to the formation of an azeotropic mixture.

To eliminate the azeotropic composition, the pressure of the system can be changed. When the pressure is reduced, the boiling point of the liquid decreases. This causes the vapor to have a different composition than the liquid, allowing for separation by simple distillation. Similarly, increasing the pressure of the system raises the boiling point of the liquid, which can also eliminate azeotropic composition.

Conclusion

Changing the pressure of the system is an effective way to eliminate azeotropic composition. This method is commonly used in the chemical industry to separate components of a mixture. However, it is important to consider the effect of pressure on the stability and reactivity of the components before implementing this method.