Question

Calculate the concentration of all species of significant concentrations present in 0.1 M H3PO4 solution. K1 = 7.5 x 10–3, K2 = 6.2 x10–8, K3 = 3.6 x10–3.

Answer 1

The value of K1 is much large than K2 and K3. Also dissociation of II and III steps occurs in presence of H+ furnished in I step and thus, dissociation of II and III steps is further suppressed due to common ion effect.

The dissociation of H2PO-4 occurs in presence of [H+] furnished in step I.