Task

The dissociation constant of acetic acid is Ka = 1.8·10⁻⁵ (25 °C). Treat the weak electrolyte with α ≪ 1. Helpful values: √1.8 ≈ 1.342; lg 1.342 ≈ 0.128; lg 4.243 ≈ 0.628; lg 1.8 ≈ 0.255; lg 5.27 ≈ 0.722; Kw = 1·10⁻¹⁴. 1) Calculate [H⁺], the degree of dissociation α (%) and the pH of 0.1 M acetic acid. 2) The solution is diluted 10 times with water. Find α (%) and pH of the new solution and explain the change in α using Ostwald’s dilution law. 3) 25 mL of 0.1 M sodium hydroxide is added to 50 mL of 0.1 M acetic acid. Calculate the pH of the resulting solution. 4) 50 mL of 0.1 M sodium hydroxide is added to 50 mL of 0.1 M acetic acid. Taking salt hydrolysis into account, calculate the pH. For every part, show the method (reaction equations, formulas, reasoning) and all calculations step by step.