Why do ammonium salts give solutions whose #pH<7#?

1 Answer
Aug 13, 2017

Answer:

The ammonium chloride salt undergoes ionization in water......

Explanation:

#NH_4Cl(s) stackrel(H_2O)rarrNH_4^+ + Cl^-#

The ammonium ion also acts as a weak acid in water to give equilibrium quantities of ammonia, #NH_3(aq)# and the hydronium ion, #H_3O^+#....

#NH_4^+ +H_2O(l) rightleftharpoonsNH_3(aq) +H_3O^+ #

The equilibrium lies to the LEFT as written, but it does operate. #pK_a=9.25# for ammonium ion.