# ionic equation for H3PO4 (aq) + NaOH (aq) ?

pls help thanks! (:

• Molecular equation:

H3PO4(aq) + 3NaOH(aq) → Na3PO4(aq) + 3H2O (l)

Full ionic equation :

3H+ (aq) + PO4 3-(aq) + 3Na+(aq) + 3OH-(aq) → 3Na+(aq) + PO4 3-(aq) + 3H2O(l)

Net ionic equation:

H+(aq) + OH-(aq) → H2O (l)

• Careful. You must realize that H3PO4 is a weak acid and will be only partially dissociated. When writing ionic equations involving weak acids, and bases, we do not show them as being completely dissociated as Upamanyu has done. Nor can we simply write the reaction of H+ and OH- as CB has done. Phosphate ion is NOT a spectator ion because H3PO4 does not dissociate completely to form H+ and PO4^3- ions.

You've asked for the "ionic equation", and so everything that exists as ions are written as ions....

H3PO4(aq) + 3Na+ + 3OH- --> 3Na+ + PO4^3- + 3HOH(l) .... as long as there is an excess of OH-

Notice that Na+ is the spectator ion, and would not be written in the "net ionic equation".

• As for all reactions of acids with hydroxides:

H+(aq) + OH-(aq) --> H2O(l)

The phosphate and sodium ions are spectator ions.

• 3H^1+ + PO4^3- + Na^1+ + OH^1- == 3Na^1+ + PO4^3- + 2H^1+ + O^2-