The Table IV in the lab manual shows the pKa values for the several buffers. You

Question

The Table IV in the lab manual shows the pKa values for the several buffers. Your "unknown" buffer sample (for Table II) will be one of the buffers in the Table IV. If the pH values of your unknown sample varied in the range of p 3.5~4.1 when you added HCI, and 4.6~5.8 when you added NaOH, which of the given buffers (in Table IV) would likely to be your "unknown" sample? Glycine (pKa1 = ~2.3) Glycine (pKa2 = ~ 9.6) Acetic acid (pKa = 4.75) Phosphate buffer (pKa1 = ~ 2.15) Phosphate buffer (pKa2 = ~ 6.82) Phosphate buffer (pKa3 = ~ 12.38)

Explanation / Answer

answer : Acetic acid (pKa = 4.75)

Explanation :

here the pH range of values = 3.5 - 4.1 , when HCl is added

pH range = 4.6 - 5.8 , when NaOH is added.

buffer pH is very slightly change when strong acid or base is added.

here the pH values range is very close to the acetic acid pKa (4.74). so this would be the unknown buffer.

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.