The topical application of an aqueous solution of ferric chloride () or alum directly to a bleeding — Surface Chemistry Chemistry Question

💡 Solution & Explanation

Human blood is fundamentally a colloidal dispersion of strictly negatively charged albuminoid substances. Highly charged cations like $Fe^{3+}$ (from $FeCl_3$) and $Al^{3+}$ (from alum) efficiently and rapidly neutralize this negative surface charge according to the Hardy-Schulze rule, causing immediate massive coagulation (clotting) that physically seals the wound.