a) Calculate the pH of a 0.015 M aspirin solution when its acid constant is Ka = 2.6 ∙ 10-5 mol/l.
b) The chemist suspected that the concentration of the aspirin solution was not accurate. So he decided to titrate 20 ml of aspirin solution with 0.05 M NaOH solution. The titration results are attached in the table. Draw the titration curve and mark the equivalent point on it. In addition, write the reaction equation and calculate the concentration of the aspirin solution tested.
On the curve, the equivalence point is located where the graph is most steep. There is a fast and abrupt change of pH around this point, which can be observed by the color change the takes place during titration. At the equivalence point, an ICE table is required to determine volume and acidity.