Please explain each step in detail.
Using chemical equations, show how the triprotic acid H3PO4 ionizes in water. Phases, such as (I) or (aq), are optional. Ka1 Ka2 Ka3 Each successive ionization reaction removes an H+ ion, so the final reaction should produce the unprotonated PO43- ion.
Answer
H-P04-(aq)-H+(aq) + HP042-(aq) HP042-(aq)-H+(aq) + PO43-(aq) Ка,-6.2x10-8 Ка,-1.7x10-12
Phosphoric acid is a weak acid and is only partially dissociated
into H+ and other ions, some of which are also weak acids. H3PO4
<==> H+ + H2PO4- Ka1 = 7.5
Pure anhydrous phosphoric acid is a white solid which melts at 42.35 °C to form a viscous liquid. In aqueous solution, phosphoric acid behaves as a triprotic acid, having three ionizable hydrogen atoms. The hydrogen ions are lost sequentially. HPo(a)H(aH,PO,) Kal-7.5x 10- HP042-(aq)-H+(aq) + PO43-(aq) Ка,-1.7x10-12 Phosphoric acid is not a particularly strong acid as indicated by its first dissociation constant. It is a stronger acid than acetic acid, but weaker than sulfuric acid and hydrochloric acid. Each successive dissociation step occurs with decreasing ease. Thus, the ion H2PO4 is a very weak acid, and HPO is an extremely weak acid.