An aqueous solution of iron(Ⅲ) chloride is:

Iron(III) chloride (${\text{FeCl}}_3$) is a salt formed from a weak base (${\text{Fe(OH)}}_3$) and a strong acid ($\text{HCl}$). When dissolved in water, it undergoes salt hydrolysis:
$${\text{Fe}}^{3+}+3{\text{H}}_2\text{O}\rightleftharpoons {\text{Fe(OH)}}_3+3{\text{H}}^{+}$$

The release of excess hydrogen ions (${\text{H}}^{+}$) makes the resulting solution acidic, with a $\text{pH}$ value less than $7$.