The pKb of aniline is 9.40 at 298 K ( $p K_{w} = 14.00$ ). Ignoring the ionisation of water and any approximation errors, the pH of a 0.10 M solution of anilinium chloride, $C X_{6} H X_{5} NH X_{3} X^{+} Cl X^{-}$ , is

A2.80
B5.20
C4.60
D9.20

Answer: A

The anilinium ion is a weak acid with pKa = 14.00 - 9.40 = 4.60. For a weak acid pH = 1/2 (pKa - log c) = 1/2 (4.60 + 1.00) = 2.80. Using the pKb directly (5.20) or pH = pKa (4.60) are common slips.

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The pKb of aniline is 9.40 at 298 K (pKw​=14.00). Ignoring the ionisation of water and any approximation errors, the pH of a 0.10 M solution of anilinium chloride, CX6​HX5​NHX3​X+ClX−, is

Answer: A

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The pKb of aniline is 9.40 at 298 K ( $p K_{w} = 14.00$ ). Ignoring the ionisation of water and any approximation errors, the pH of a 0.10 M solution of anilinium chloride, $C X_{6} H X_{5} NH X_{3} X^{+} Cl X^{-}$ , is