What is meant by the symbol Ka3 for H3PO4?

Write the corresponding equilibrium.

Answer 1

Ka is the dissociation constant for an acid,
Since H3PO4 has three acidic protons it has 3 Ka values
Ka1 is the removal of the first proton H3PO4 –> H2PO4{-}
Ka2 is the removal of the 2nd proton H2PO4{-} –> HPO4{2-}
Ka3 is the removal of the 3rd proton HPO4{2-} –> PO4 {3-}

HPO4{2-}(aq) + H2O(l) —-> H3O+ (aq) + PO4{3-} (aq)

Ka = products / reactants
Treat it as any other acid/base problem now

Leave a Comment