Aniline, C₆ H₅ NH₂ , Is Commonly Used as a Precursor

Multiple Choice

Aniline, C₆ H₅ NH₂ , is commonly used as a precursor for making dyes. Aniline is a base when dissolved in water. It ionizes as shown below. What is the base ionization constant, K b , of aniline if an aqueous 0.20 M C₆ H₅ NH₂ solution has a pOH value equal tO₅ .05?
C₆ H₅ NH₂ + H₂ O C₆ H₅ NH₃+ + OH -

A) K _b = 6.3×10 ^{- 18}
B) K _b = 4.0×10 ^{- 10}
C) K _b = 4.5×10 ^{- 5}
D) K _b = 1.5×10 ^{- 2}
E) K _b = 6.3×10¹⁰