Titration Curves

How Can We Graph Titrations?

This post will go through graphing titration curves for QCE Chemistry.

3.1.7 – Volumetric Analysis

• Sketch the general shapes of graphs of pH against volume involving strong and weak acids and bases. Identify and explain their important features, including the intercept with pH axis, equivalence point, buffer region and points where pKa = pH or pKb = pOH

Acid-Base Titration Curves

This video will go through the general shapes where the titrant is a base. Note that if the titrant was an acid, the graph would be flipped.

Additional Information on Titration Curves

Titration curves are graphical representations of the progress of a titration, a laboratory technique used to determine the concentration of a solution. A titration is a process in which a solution of known concentration (the titrant) is added to another solution (the analyte) of unknown concentration until the reaction between them is complete. The progress of the titration is usually monitored by measuring the pH or the potential of an electrode (in case of redox titrations) of the analyte solution as the titrant is added.

The titration curve is a plot of the pH (or the potential) of the analyte solution versus the volume of titrant added. The shape of the titration curve depends on the type of acid-base or redox reaction taking place, and on the relative strengths of the acid and base or the oxidant and reductant.

At the start of the titration, the pH of the analyte solution is that of the acid or the reduced species (in case of redox titrations) before the addition of the titrant. As the titration proceeds, the pH changes as the acid and base or the oxidant and reductant react. The pH change is more gradual at the beginning of the titration, then becomes more rapid as the end point of the titration approaches.

The end point of the titration is the point at which the acid and base or the oxidant and reductant have reacted in stoichiometric amounts. This is usually indicated by a sudden change in the pH or the potential of the analyte solution, such as a colour change in the indicator or a sharp change in the electrode potential.

Knowing the shape of the titration curve and the endpoint of the titration, one can calculate the concentration of the analyte solution. This process is called titrimetry and it is widely used in analytical chemistry and other fields.