What volume of 0.5 M sodium acetate solution (in mL) should be added to 100 mL of 0.2 M acetic acid to produce a buffer of $pH = 5.05$ at $2 5^{\circ} C$ ?
Given $p K_{a}$ of acetic acid $= 4.75$ ; $lo g 2 = 0.3$ .

Question

What volume of 0.5 M sodium acetate solution (in mL) should be added to 100 mL of 0.2 M acetic acid to produce a buffer of $pH = 5.05$ at $2 5^{\circ} C$ ?

Given $p K_{a}$ of acetic acid $= 4.75$ ; $lo g 2 = 0.3$ .

TestHub · Accepted Answer

pH = p K a ​ + lo g [ acid ] [ salt ] ​ : 5.05 = 4.75 + lo g ( ratio ) , so the ratio = 2 . Acid = 100 × 0.2 = 20 mmol, so salt = 40 mmol. V = 40/0.5 = 80 mL. Answer: (B).

Chemistry - Ionic Equilibrium Question with Solution | TestHub

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