Acid dissociation constants for phosphoric acid are given below. A buffer with a pH = 7.4 can best be made by using

Question

Acid dissociation constants for phosphoric acid are given below.  A buffer with a pH = 7.4 can best be made by using

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To make a buffer with a pH of 7.4 using phosphoric acid, we need to use a mixture of its conjugate base and acid form. The pKa values given in the table are 2.14, 6.86, and 12.4. At pH 7.4, the predominant form of phosphate is H2PO4-. B) NaH₂PO₄ and Na₂HPO₄ would provide both the H2PO4- and HPO42- forms of phosphate, giving a suitable buffer system.

Acid Dissociation Constants for Phosphoric Acid Are Given Below