It is possible to make two completely different buffers using the dihydrogen phosphate ion, H₂PO₄^–.

(a) In one buffer, H₂PO₄^– serves as the weak acid. What is the conjugate weak base?

(b) Write the equations that show how the buffer in part (a) works when either H₃O⁺ or OH^– is added.

(c) In the other buffer, H₂PO₄^– serves as the weak base. What is the conjugate weak acid?

(d) Write the equations that show how the buffer in part (c) works when either H₃O⁺ or OH^– is added.