You work in a medical research lab with a biochemist who asksyou to make a 1.00 L phosphate buffer stock solution with pH = 7.4.The total phosphorus concentration is to be 0.250 M. In thestoreroom, there are the following reagents: (1) a 3.00 Mphosphoric acid stock solution, (2) solid sodium dihydrogenphosphate, (3) solid sodium monohydrogen phosphate, (4) solid,sodium phosphate, (5) a 3.00 M HCl(aq) stock solution, (6) a 3.00 MNaOH(aq) stock solution, and (7) deionized water.
(i) (2 pts) To make an optimum buffer, it is important that thepKa of the acid part is close to the target pH of the buffer. Whichphosphate species has a pKa value closest to pH = 7.4?
(ii) (4 pts) Choose this phosphate species (in i) as the onlyphosphorus component. What amounts of this substance and any otherreagents (grams of solid(s); mL of any solution(s) and water) wouldyou need to make the buffer with pH = 7.4?
(iii)(4 pts) Choose this phosphate species (in i) and either itsconjugate acid or base as the only two phosphorus components. Whatamounts of this substance, its conjugate acid or base, and water(grams of solid(s); mL of any solution(s) and water) would you needto make the buffer with pH = 7.4?
