A Phosphate Buffer Solution (25

Multiple Choice

A phosphate buffer solution (25.00 mL sample) used for a growth medium was titrated with 0.1000 M hydrochloric acid. The components of the buffer were sodium monohydrogen phosphate and sodium dihydrogen phosphate. The first endpoint occurred at a volume of 10.32 mL, and the second occurred after an additional 18.62 mL was added, for a total volume of 28.94 mL. What was the total concentration of phosphate (in any form) in the buffer?

A) 0.03992 M
B) 0.1198 M
C) 0.04243 M
D) 0.07448 M
E) 0.08382 M