PART ONE: A buffer solution contains 0.22 mol of acetic acid (HC2H3O2) and 0.77
ID: 958736 • Letter: P
Question
PART ONE:
A buffer solution contains 0.22 mol of acetic acid (HC2H3O2) and 0.77 mol of sodium acetate (NaC2H3O2) in 3.40 L.
The Ka of acetic acid (HC2H3O2) is Ka = 1.8e-05.
(a) What is the pH of this buffer?
pH = ____
(b) What is the pH of the buffer after the addition of 0.16 mol of NaOH? (assume no volume change)
pH = ____
(c) What is the pH of the original buffer after the addition of 0.41 mol of HI? (assume no volume change)
pH =____
PART TWO:
(a) Calculate the percent ionization of 0.00180 M hypochlorous acid (Ka = 3e-08).
% ionization = ______%
(b) Calculate the percent ionization of 0.00180 M hypochlorous acid in a solution containing 0.0120 M sodium hypochlorite.
% ionization = ______%
Explanation / Answer
a) pka = -log(1.8*10^-5) = 4.74
pH = 4.74+log(0.77/0.22) = 5.28
b)
pH = 4.74+log((0.77+0.16)/(0.22-0.16)) = 5.93
c)
pH = 4.74+log((0.77-0.41)/(0.22+0.41)) = 4.49
part 2
kA = C*X^2
(3*10^-8) = (0.0018*X^2)
X = 0.0041
percent ionisation = x*100
= 0.0041*100 = 0.41%
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