Hydrolysis constant - Hydrolysis constant

The equilibrium constant for the hydrolysis of the conjugate acid (or conjugate base) of a weak base produced by the ionization of the salt produced by the neutralization of a weak base and a strong acid (or a weak acid and a strong base, or a weak base and a weak acid). The NH ₄ ⁺ produced by the neutralization of the weak base NH ₃ with the strong acid HCl is,

NH ₄ ⁺ + H ₂ O NH ₃ + H ₃ O ⁺

If the hydrolysis constant is K _h , then

K _h = c _{NH 3} × c _{H 3 O ⁺} / c _{NH 4 ⁺}
On the other hand, the ionization constant of NH ₃ in aqueous solution is

K _b = c _{NH 4 ⁺} × c _{OH ^-} / c _{NH 3}
Since the ionic product of water is Kw _,

KhKb _{= Kw​}​​
This relationship also holds true for weak acids and strong bases.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

弱塩基と強酸(または弱酸と強塩基，弱塩基と弱酸)の中和で生じた塩の電離で生じる弱塩基の共役酸(または弱酸の共役塩基)が加水分解する反応の平衡定数．弱塩基 NH₃ と強酸HClの中和で生じる NH₄^＋ は，

NH₄^＋ ＋ H₂O NH₃ ＋ H₃O^＋

の加水分解を行う．加水分解定数を K_h とすれば，

K_h ＝ c_NH3 × c_H3O^＋/c_NH4^＋
一方，水溶液中での NH₃ の電離定数は

K_b ＝ c_NH4^＋ × c_OH^－/c_NH3
水のイオン積は K_w であるから，

K_hK_b ＝ K_w
この関係は弱酸と強塩基の場合にも成り立つ．

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