[b]1. The problem is need to prepare 400.0 mL of a .200M buffer having a pH of 7.69
Given .5 M of dihydrogen Phosphate at pKa of 6.82
[b]2. Equation to work from is Henderson-Hasselbalch pH=pKa-log of (A-)/(HA)
where (A-) is weak acid and (HA) is the conjugate base
[b]3. I...