5. Phosphate ions are abundant in cells, both as the ions themselves and as important sub- stituents on organic molecules. Most importantly, the pK, for the H,PO, ion is 7 20, which is very close to the normal pH in the body. H,PO, (aq) + H,0(1) = HPO, (aq) + H,0 (aq) a. What should the ratio [HPO,1/[H,PO,] be to control the pH at 7.4? b. A typical total phosphate concentration in a cell, [HPO,]+ [H,PO, ], is 2.0 x 10- M. What are the concentrations of HPO, and H,PO, at pH 7.4? 2-