Introduction (Titration)

Introduction

Titration is one of the quantitative chemical analysis. It is an analytical technique which allows a solution of known concentration added quantitatively to a known volume of a solution of unknown concentration in order to determine its concentration. In this experiment, acid-base titration is carried out. There are different types of titration such as strong acid-strong base titration, weak acid-strong base titration and strong acid-weak base titration. The purpose of the titration is to detect the equivalence point which is the point when a stoichiometric amount of the titrant has been added to react with the titrand to be determined.

Equivalence point is the point in a titration when a stoichiometric amount of the standard solution has been added to react with the substances to be determined. End point is the point at which the indicator changes colour in a titration.

A suitable indicator is needed to detect the end point, a point at which the indicator changes colour in the titration.

Acid-base indicators change colour over a small range of pH. A suitable indicator should be chosen such that the end point of titration occurs at the equivalence point, then the colour change in the solution being titrated can be used as the signal that the equivalence point has been reached. Every indicator has different change in colour and pH range. The indicator chosen must change colour over a pH range that is within the steep vertical region or near the equivalence point in order to determine the equivalence point accurately using the indicator.

Besides that, the pH meter is used to measure pH of the solution. A titration curve is a graph showing the pH of an acid or base solution as a function of amount of titrant added. The point of the greatest slope on the titration curve is estimated as the equivalence point. Titration curves obtained are different for different types of acid-base titrations.