Calculate the pH of an aqueous solution of sodium hydrogenphosphite, NaHPO₃. For phosphorous acid, H₂PO₃, pK_a1 = 2.00 and pK_a2 = 6.59.

Question

Quizplus · Accepted Answer

The pH of the solution can be approximated by the average of the pKa1 and pKa2 of phosphorous acid, since sodium hydrogenphosphite (NaH2PO3) is a salt of the diprotic phosphorous acid (H3PO3) and will partially dissociate in water to form H2PO3^- ions, which can then lose a proton to form HPO3^2- ions. The average of the pKa values (2.00 and 6.59) gives a pH of approximately 4.30.

Calculate the PH of an Aqueous Solution of Sodium Hydrogenphosphite