Hydrogen Bonding

Step 1: Understanding the behavior of o-nitrophenol.
O-nitrophenol (ortho-nitrophenol) exhibits intermolecular hydrogen bonding between the hydrogen of the hydroxyl group and the oxygen of the nitro group in the ortho position. This intermolecular hydrogen bonding increases the boiling point of o-nitrophenol compared to p-nitrophenol, which does not have this type of hydrogen bonding.
Step 2: Effect of intermolecular H-bonding.
Intermolecular hydrogen bonding in o-nitrophenol reduces its volatility under normal conditions. However, during steam distillation, o-nitrophenol can still be separated due to the relatively weaker intermolecular forces compared to p-nitrophenol, which lacks such bonding.
Step 3: Conclusion.
Thus, o-nitrophenol can be separated from p-nitrophenol via steam distillation due to the presence of intermolecular hydrogen bonding in o-nitrophenol.