A buffer is made using only Tris (weak base) and HCl. What is the volume, of 1.7 M HCl that would be used to make 0.50 L of a buffer solution with a total buffer concentration ([Tris] - [TrisH+]) of 0.15 M, and pH of 7.9?

TrisH+ + H2O <--> Tris + H3O

pKa (TrisH+) = 8.30