A Phosphate Buffer Solution (25

question 65

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 monohydrogenphosphate and sodium dihydrogenphosphate. The first endpoint occurred at a volume of 10.32 mL; the second occurred after an additional 18.62 mL was added (or total volume = 28.94 mL) . What was the approximate ratio of HPO₄^2- to H₂PO₄^- in the buffer?

• A) 1:1
• B) 4:5
• C) 5:3
• D) 5:4
• E) 3:5

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The likelihood of seeing test outcomes that are as extreme or more so than the actually observed results, assuming the null hypothesis is true.

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