Concept Check: Acid-Base Definitions

Hemoglobin, shown below, consists of an iron (II) center in its deoxygenated state coordinated by four pyrrole molecules. When oxygen binds to the heme center it is acting as a:

Which of the following chemical species can be classified as a Brønsted–Lowry acid based on the reaction below?

NH₄Cl + NaCH₃COO ⇋ NaCl + NH₃ + CH₃COOH

Which of the following pairs correctly displays the behavior of an amphoteric compound?

I) H₂O + S^2- →OH^– + HS^– and H₂SO₄ + H₂O → H₃O⁺ + HSO₄^–

II) HCl + NaOH → H₂O + NaCl  and HCl + NH₃ →NH₄Cl

III)  H₂PO4^– + OH^– → HPO₄^2- + H₂O and H₂PO₄^– + H₃O⁺ → H₃PO₄ + H₂O