In: Chemistry
How many grams of NaOH must be added to 1.0 L of 2.0 M HC2H3O2 to produce a buffer solution with a pH = 4.80.
Ka = 1.8 × 10-5
moloes of CH3COOH = 1.0 x 2.0 = 2.0
moles of NaOH = X
CH3COOH + NaOH --------------------> CH3COONa + H2O
2.0 X 0 0
2.0-X 0 X X
pH = pKa + log [CH3COONa / CH3COOH]
4.80 - 4.74 = log (X / 2-X)
0.06 = = log (X / 2-X)
X / 2-X = 10^0.06
X / 2-X = 1.148
2.148 X = 2.296
X = 1.069
moles of NaOH = 1.069
mass of NaOH = 1.069 x 40
= 42.8 g
mass of NaOH = 42.8 g