Biochemists frequently use "phosphate" buffers in their work. Here, "phosphate" refers generally to the class of phosphate derived ions:
H₂PO₄⁻ , HPO₄²⁻, PO₄³⁻ .
(a) Which of these ions best represents the conjugate acid in a "phosphate" buffer at physiological pH? Explain.
(b) A buffer used in an experiment was described as "a 0.2 M phosphate buffer with pH = 7.25." Based on the conjugate acid you identified in (a), determine the concentration of conjugate acid in this "0.2 M phosphate buffer."