Assertion (A): O-Nitro phenol has intramolecular hydrogen bond.
Reason (R): O-Nitro phenol is more volatile than p-Nitro phenol.
Answers
Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
O-nitrophenol contains intramolecular hydrogen bonding between hydrogen of hydroxyl group and oxygen of nitro group. Due to this the hydrogen atom of hydroxyl group is firmly attached to molecule and cannot be easily lost.
Such intramolecular hydrogen bonding is not present in p-nitrophenol. Thus, p-Nitrophenol is stronger acid than o-nitrophenol. This is also supported by pKa values. The pK a of pnitrophenol is 7.1 which is lower than that of o-nitrophenol (pKa=7.2). Stronger acid has lower pKa value.
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Answer:
Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
O-nitrophenol contains intramolecular hydrogen bonding between hydrogen of hydroxyl group and oxygen of nitro group. Due to this the hydrogen atom of hydroxyl group is firmly attached to molecule and cannot be easily lost.
Such intramolecular hydrogen bonding
is not present in p-nitrophenol. Thus, p-Nitrophenol is stronger acid than o-nitrophenol. This is also supported by pKa values. The pK a of pnitrophenol is 7.1 which is lower than that of o-nitrophenol (pKa=7.2). Stronger acid has lower pka value.