Suppose you are working in a Biochemistry lab and the pH meter is broken. You urgently need to make a phosphate buffer at pH 7.8. From an inspection of your chemical inventory you note that you have the following forms of phosphate to make your buffer: phosphoric acid (H3PO4), mono-basic sodium phosphate (NaH2PO4), di-basic sodium phosphate (Na2HPO4) and tri-basic sodium phosphate (Na3PO4). You then find in your Biochemistry textbook that the 3 pKaS for phorphoric acid are pKa1 = 2.15, pKa2 = 7.2 and pKa3 = 12.4 In order to make 1 L of a 0.1 M sodium phosphate buffer at pH 7.8 how many moles of which compounds would you mix together? Show all your work.
