Why is ammonia not an arrhenius base?

1 Answer
anor277
May 27, 2018

Well, Arrhenius bases are conceived to be sources of the hydroxide ion in aqueous solution...

Explanation:

And since ammonia does NOT contain hydroxide ions, i.e. its chemical formula is #NH_3#, it does not fall under the Arrhenius' umbrella. We classify ammonia as a Bronsted-Lowry base...and its conjugate acid is ammonium ion, #NH_4^+#...

#NH_3(aq) + H_2O(l) rightleftharpoonsNH_4^+ + HO^-#

#K_b=1.80xx10^-5#

Note that this is all conceived to occur in AQUEOUS solution, i.e. in a water solvent. In liquid ammonia solvent, and use of this solvent is nowadays fairly standard and straightforward....the following acid-base regime obtains...

#2NH_3(l)rightleftharpoonsunderbrace(NH_2^(-))_"the amide ion" + NH_4^+#

Ammonia has a normal boiling point of #33.3# #""^@C#...
The degree of dissociation can be measured, but I don't my text at hand right now....

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