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Problem 8 - Olympiad

A buffer solution is prepared by mixing 100 mL of 1 M acetic acid with 100 mL of 1 M sodium acetate. What is the pH of the resulting solution, given that the dissociation constant (Ka) of acetic acid is 1.8 x 10^-5?

Correct: A

To find the pH of the buffer solution, we can use the Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]), where [A-] is the concentration of the conjugate base (sodium acetate) and [HA] is the concentration of the weak acid (acetic acid). First, we need to find the concentrations of [A-] and [HA] after mixing, then apply the equation.