In: Chemistry
You need to prepare an acetate buffer of pH 5.52 from a 0.881 M acetic acid solution and a 2.64 M KOH solution. If you have 875 mL of the acetic acid solution, how many milliliters of the KOH solution do you need to add to make a buffer of pH 5.52? The pKa of acetic acid is 4.76.
pH of acidic buffer = pka +
log(ch3cooK/CH33COOH)
pH = 4.9
pka of CH3COOH = 4.76
no of mol of CH3COOH = M*V
= 0.881*0.875
= 0.771 mol
No of mol of CH3COOK = KOH = x mol
5.52 = 4.76+log(x/(0.771-x))
x = 0.657
No of mol of CH3COOK = KOH = 0.657 mol
volume of KOH required = n/M
= 0.657/2.64
= 0.25 l
= 250 ml