Titration is a chemical reaction that results from the quantitative addition of a solution of known concentration to one of unknown concentration. Acid-base titrations are among the most common when a standard sodium hydroxide solution is added to a hydrochloric acid solution, the neutralization reaction occurs. A pH meter is employed to measure the acidity of the solution. To illustrate, let’s add 0.100 molar base to precisely 50 mL of a 0.100 molar acid solution. The pH increases slowly at first. As the amount of base added approaches that required for complete neutralization, that is the stoichiometrically-equivalent amount, the pH begins to increase more rapidly. The last few drops of added base change the pH from about 3.0 to 7.0. The pH is 7.0 when precisely 50 mL of base have been added. We are then at the equivalence point, or endpoint, at which the stoichiometric amount, base required to neutralize the acid, has been added. Addition of one drop of NaOH beyond that needed to neutralize the acid, causes the pH to increase from 7.0 to about 10.0. Thus, the endpoint of the titration can be determined with high precision.
Scientific and Medical Animations
Copyright ©2017 ALL RIGHTS RESERVED