Weak Acid Dissociation Lab Report

The purpose of the Weak Acid Dissociation experiment is to determine the dissociation constant of a weak acid experimentally by using acid-base titration with a strong base and stoichiometry. An acid-base titration is a method by which a basic (or acidic) solution of unknown concentration is reacted with an acidic (or basic) solution of known concentration. (1) The pH in acid-base titration is measured using a pH meter or color changing indicator, such as phenolphthalein, as the known solution is added slowly to the unknown. (1) The equivalence point or end point of the titration is visually indicated by the color change from the indicator, and is where the moles of base and acid are stoichiometrically equal. (1) The concentration, or molarity of the unknown substance can then be calculated from the titration data, utilizing the equivalence point, the concentration and amount of known substance reacted and the volume of the unknown substance titrated. (2)
(3) Strong acids and bases are strong electrolytes and dissociate completely in aqueous solutions. (1) Weak acids and bases are weak electrolytes and only partly ionize in water. (3) Six important strong acids include HCl, HBr, HI, HNO3, HClO4, and H2SO4. (1) Monoprotic acids, like the first five strong acids listed, have one proton that will ionize in aqueous solution. H2SO4 is a diprotic acid, and has two protons that will dissociate in water. (1) In aqueous solution, a more stable ion is formed when the donated proton H+ from a strong acid bonds with water to form the hydronium ion H3O+. (2) This is illustrated with the