Question

You need to prepare an acetate buffer of pH 6.29 from a 0.704 M acetic acid solution and a 2.48 M KOH solution. If you have 575 mL of the acetic acid solution, how many milliliters of the KOH solution do you need to add to make a buffer of pH 6.29? The pKa of acetic acid is 4.76.

You need to prepare an acetate buffer of pH 6.29 from a 0.704 M acetic acid solution and a 2.48 M KOH solution. If you have 575 mL of the acetic acid solution, how many milliliters of the KOH solution do you need to add to make a buffer of pH 6.29? The pKa of acetic acid is 4.76 Number mL IIn

Answer 1

0.704 mmol = 404.8 mmol No of moles of CH3COOH = 575 mL × pH of the buffer= 6.29 pK, of weak aci d CHCOOH, pK, -4.76 mL ICE table I mmo 404.8 C(mmol) (mmo 404.8-x According to Henderson equation, CH COO pH = pKa + log 6.29 = 4.76 + log 404.8-x log1.53 404.8-х 1013 33.9 x=393.2 mmol According to the ICE table, no of moles of base added-x mmol 404.8-x 393.2 mmmol 1 mL =158 mL 2.48 mmol Volume of KOH added-393.2 mmol