Question

A buffer solution contains 0.76 mol of propionic acid (HC3H5O2) and 0.65 mol of sodium propionate (NaC3H5O2) in 3.40 L. The Ka of propionic acid (HC3H5O2) is Ka = 1.3e-05. (a) What is the pH of this buffer?

pH =

(b) What is the pH of the buffer after the addition of 0.18 mol of NaOH? (assume no volume change)

pH =

(c) What is the pH of the original buffer after the addition of 0.54 mol of HI? (assume no volume change)

pH =

Answer 1

HC 3 H 5 O2 + H₂O C₃H07 + H₂ot I PH = pka + log (C₂H5O₂ Handerson Hasselbaka HC 3 H 5 Og equation. 2 pka = -log ka = -log (1.3x10-5) Pka = 4.89 | PH = 4.89 + log (0.65 pH = 4.89 0.76 volume is same so cancel out. LPH = 4.89 + (-0.07) LPH = 4.82 | - (6) HC ₂ H 5 O₂ I 0.76 c-0.18 E 0.58 + NaOH 0.18 0.18 o 3 H50,- + H₂O 0.65 +0.18 0.83 0.58 0.83 pH = 4.89 + log PH = 4.89 + 0.16 (pH = '5.05

c) After addition of HI I C E C3H50- 0.65 -0.54 0.11 + HI 0.54 -0.54 0 НС, НО, 0.76 +0.54 1.30 PH - 4.89 + rogol = 4.89 + (-1-07) PH = 3.82