To calculate the pH of a 0.1 M solution of acetic acid, we can use the formula for the ionization constant Ka of a weak acid:Ka = [H+][A-] / [HA]Where [H+] is the concentration of hydrogen ions, [A-] is the concentration of the conjugate base acetate ions , and [HA] is the concentration of the undissociated acetic acid.Since the initial concentration of acetic acid is 0.1 M, we can assume that the change in concentration due to ionization is small. Let x be the concentration of hydrogen ions and acetate ions after ionization:Ka = x x / 0.1 - x Given that Ka = 1.8 x 10^-5, we can substitute this value into the equation:1.8 x 10^-5 = x^2 / 0.1 - x Since x is small compared to 0.1, we can approximate the equation as:1.8 x 10^-5 x^2 / 0.1Now, we can solve for x:x^2 1.8 x 10^-5 * 0.1x^2 1.8 x 10^-6x 1.8 x 10^-6 x 1.34 x 10^-3Now that we have the concentration of hydrogen ions [H+], we can calculate the pH using the formula:pH = -log[H+]pH = -log 1.34 x 10^-3 pH 2.87Therefore, the pH of a 0.1 M solution of acetic acid is approximately 2.87.