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Chapter 3: Problem 133

Identify the wrong statement. (a) Phenols are stronger acids than alcohols, but weaker than carboxylic acids (b) Phenols, being stronger acids, are soluble in aqueous \(\mathrm{NaOH}\) solution and in saturated \(\mathrm{NaHCO}_{3}\) solution. (c) Phenols are acidic because of resonance stabilization of the phenoxide ion formed by ionization. (d) The \(\mathrm{pK}_{\mathrm{a}}\) of phenol is about \(10 .\)

Short Answer

Expert verified
a) Phenols are stronger acids than alcohols but weaker than carboxylic acids. b) Phenols are soluble in both aqueous NaOH and saturated NaHCO3 solutions. c) Phenols are acidic due to resonance stabilization of the phenoxide ion formed by ionization. d) The pKa value of phenol is around 10. Answer: b) Phenols are soluble in both aqueous NaOH and saturated NaHCO3 solutions.

Step by step solution

01

Statement (a)

Phenols are indeed stronger acids than alcohols but weaker than carboxylic acids. This is due to the presence of the hydroxyl group (-OH) attached to the aromatic ring in the phenol molecule, which makes it more acidic than a simple alcohol but less acidic compared to a carboxylic acid. So, this statement is correct.
02

Statement (b)

Phenols are soluble in aqueous NaOH solution due to the formation of water-soluble phenoxide ions. However, they are not soluble in saturated NaHCO3 solution. Carboxylic acids, which are stronger acids than phenols, are the ones that can react with NaHCO3 and be soluble in it. Thus, this statement is incorrect.
03

Statement (c)

Phenols become acidic due to resonance stabilization of the phenoxide ion formed by ionization. When a phenol molecule loses a proton, the negative charge formed on the oxygen atom can delocalize on the aromatic ring, leading to the resonance stabilization of the phenoxide ion. This makes phenols acidic in nature. So, this statement is correct.
04

Statement (d)

The pKa value of phenol is indeed around 10, which is another indication of its acidity. A lower pKa value corresponds to a stronger acid, so phenol is moderately acidic. This statement is correct. To conclude, the wrong statement among the given options is statement (b). Phenols, being stronger acids than alcohols, are soluble in aqueous NaOH solution but not in saturated NaHCO3 solution.

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Most popular questions from this chapter

$$ \begin{array}{l} \text { The organic product (X) formed in the following reaction is }\\\ \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2} \mathrm{Cl}+\mathrm{C}_{6} \mathrm{H}_{5} \stackrel{\mathrm{AICl}_{3}}{\longrightarrow} \mathrm{X} \end{array} $$

Statement 1 Phenoxide ion is more reactive than phenol towards electrophiles. and Statement 2 Phenoxide ion is stabilized more by resonance than phenol.

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