Phosphate has three ionizable groups, and thus can serve as a buffer at various pH ranges. a. What are the pH ranges over which phosphate-derived buffers could be useful? 5.88.0 b. What are the two predominant species (>10%) in my Phosphate buffer at pH7.5 ? Which pKa would I use in further calculations? here i. pKa1=2.1,pKa2=7.2,pKa3=12.3 c. What is the net charge of the solution at pH7.0 ? here d. If I had 2.0M stock of sodium dihydrogen phosphate and 2.0M stock of sodium mono-hydrogen phosphate, how much of each would I use to make a liter of 30mM phosphate buffer at pH 7.5 ? here