Question

The best method for the separation of o-nitrophenol and p-nitrophenol from their mixture is:

• A. Crystallisation
• B. Steam distillation
• C. Sublimation
• D. Simple distillation

Hint:

Steam distillation is useful for separating liquids that have significantly different boiling points, especially if one of them has a high boiling point due to intermolecular forces like hydrogen bonding.

Answer 1

The Correct Option is B

Step 1: Understand the properties of o-nitrophenol and p-nitrophenol.
o-Nitrophenol and p-nitrophenol are two isomers with different physical properties. The key difference between these two compounds is their boiling points, which will determine the method used for separation.

Step 2: Analyze the boiling points.
- o-Nitrophenol has a higher boiling point than p-nitrophenol because the intramolecular hydrogen bonding in o-nitrophenol makes it more stable and harder to vaporize.
- p-Nitrophenol, on the other hand, has a lower boiling point due to the absence of intramolecular hydrogen bonding.

Step 3: Identify the separation method.
The best way to separate compounds with differing boiling points is through steam distillation. Since steam distillation occurs at a temperature lower than the boiling points of the individual compounds, it is an effective method to separate o-nitrophenol and p-nitrophenol.

Step 4: Conclusion.
Therefore, the correct method for separating o-nitrophenol and p-nitrophenol is steam distillation, and the correct answer is option (B).