When Ammonium chloride is in an aqueous medium its cation part ammonium undergo hydrolysis. Since ammonium is conjugate acid of a weak base it readily release one $\ce{H+}$ and converts back to $\ce{NH3}$. But its given in my textbook that hydrolysis of Ammonium chloride gives ammonium hydroxide. Why Ammonium hydroxide is formed instead of staying as ammonia? Because according to my understanding ammonium hydroxide is formed when ammonium ion and hydroxide ion attract each other to have an ionic bond, and since ammonium ion converts back to ammonia how is this possible?
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1$\begingroup$ No, there is not ammonium hydroxide, except as a very minor and non-isolable component. The hydrolysis product is overwhelmingly just plain ammonia. $\endgroup$– Oscar LanziJun 2, 2019 at 1:31
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1 Answer
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When ammonium chloride is hydrolyzing, there is established equilibrium
$$\ce{NH4+ + H2O <<=> NH3 + H2O+}$$
with $$\mathrm{pH}=7-\frac 12 ( 4.75 + \log {c_{\ce{NH4Cl}}} )$$
$$\mathrm{pOH}=14 - \mathrm{pH}=7+\frac 12 ( 4.75 + \log {c_{\ce{NH4Cl}}} )$$
Concentration of ammonia is several orders higher than concentration of hydroxide ions, with origin of water dissociation, so no ammonia hydroxide there.
When ammonia is dissolved, there is established equilibrium
$$\ce{NH3 + H2O <<=> NH4+ + OH-}$$
with $$\mathrm{pH}=14-\frac 12 ( 4.75 - \log {c_{\ce{NH3}}} )$$
Equimolar concentrations of $\ce{NH4+ + OH-}$ are sometimes formally called ammonium hydroxide, but using this term is deprecated and it cannot be isolated.
