You want to make 100 mL of 0.30 M acetic acid buffer with pH 5.0. You are given

Question

You want to make 100 mL of 0.30 M acetic acid buffer with pH 5.0. You are given a stock of 10 M acetic acid and a bottle of solid sodium acetate salt (MW-82g/mol). The formula for the dissociation of acetic acid is shown here. The Henderson-Hasselbalch equatión is: pH pka log [A/HA pKa 4.75 CHCOOHCH 1. What is the ratio of [A VIHA] when your buffer pH is 5.0? tn) A- 6.0 47s t loa -25 -2. Determine the concentrations of weak acid and conjugate base in the buffer. Don't forget units! HA000 IA]- 3. How many mLof 1.0 M acetic acid will you need? 4. How many grams of sodium acetate salt will you need? 100ml 0.1 If you now add 1 mL of 1M NaOH to your buffer, what would be the resulting pH? pH = Will you still have a valid buffer? Circle one: Yes No

Explanation / Answer

1) we have for the reaction

CH3COOH <---------------> CH3COO- + H+

and

pH = pKa + log[A-]/[HA]

where

pH = 5.0

pKa = 4.75

therefore putting the values , we get

5.0 = 4.75 + log[A-]/[HA]

or

log[A-]/[HA] = 5.0 - 4.75 = 0.25

or

[A-]/[HA] = 10^0.25 = 1.78

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

---

---

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