1. Consider the following: Phosphoric acid (H₃PO₄), phosphorous acid (H₃PO₃) hypophosphorous acid (H₃PO₂) and the arsenic analogues (H₃AsO₄, H₃AsO₃ and H₃AsO₂).
1. Estimate the approximate pKa of H₃PO₄, H₃PO₃, H₃PO₂ and H₃AsO₄. ]
2. Refine your estimate by deciding if H₃PO₄ or H₃AsO₄ is stronger.
3. Phosphorous acid can exist in the two tautomeric forms show to the right. From the pKa of phosphorous acid (1.8), assign a structure to the form of phosphorous acid you would expect in aqueous solution.
4. The pKa of hypophosphorous acid is 2.00. Assign a reasonable structure.
5. Summarize your thinking in a well-organized paragraph.