You are asked to prepare 500. mL of a 0.150 M acetate buffer at pH 5.10 using on

Question

You are asked to prepare 500. mL of a 0.150 M acetate buffer at pH 5.10 using only pure acetic acid (MW = 60.05 g/mol, pK_a = 4.76), 3.00 M NaOH, and water. Answer the following questions regarding the preparation of the buffer. How many grams of acetic acid will you need to prepare the 500 mL buffer? What volume of 3.00 M NaOH must you add to the acetic acid to achieve a buffer with a pH of 5.10 at a final volume of 500 mL? (Ignore activity coefficients.) Pour the beaker contents into a 500 mL volumetric flask. Rinse the beaker several times and add the rinses to the flask. Swirl the flask to mix the solution. Add water to the mark to make the volume 500 mL. Stopper the flask and invert how many times to ensure complete mixing?

Explanation / Answer

1. acidic buffer

pH = pka + log(salt/acid)

concentration of aceticacid = 0.15*0.5 = 0.075 mole

mass of aceticacid = 0.075*60.05 = 4.50375 grams

2.

5.1 = 4.76 + log(x/(0.075-x))

x = 0.0515 mole

No of moles of NaOH = 0.0515 mole

Volume of NaOH = n/M = 0.0515/3 = 0.01716 L

          = 17.16 ml

3. maximum time will give you the 100% mixing.

= 20

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

---

---

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