Question

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

Answer 1

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.