Titrations

Titration is a technique to determine the unknown concentration of a substance (the analyte) by reacting it with a substance of known concentration (the titrant). Often, an indicator is added to the reaction vessel to determine when the two reactants are in the correct stoichiometric ratio. Once the correct ratio is achieved (known as the equivalence point), a color change occurs. This color change signals when no more titrant should be added.

Titrations are performed by:

Cleaning a buret with a small amount of the titrant.
The buret is filled with the titrant and drained to the 0.00 cm3 mark.
A known amount (e.g., mass or volume) of the analyte is added to a container (e.g., a beaker). The container is placed below the buret.
The initial volume in the buret is recorded.
While mixing and stirring the analyte, the titrant is added. Once a permanent color color change occurs, the titrant is no longer added and the final volume of the titrant is recorded, often to the nearest 0.05 cm3 mark.

Above: The general process of performing an acid-base titration. From: https://www.reagent.co.uk/wp-content/uploads/The-/ro/The-process-of-titration-graphic-scaled-1.jpg.webp

The first titration is often performed with less precision than subsequent titrations as the amount of titrant required is unknown. The following titrations are performed with more precision as the volume of titrant required is known.

The equivalence point of a titration can also be determined using other means. Continually monitoring the pH, electrical conductivity or temperature of the analyte using probes generates graphs with distinct appearances. Certain points on the graph corresponds to the equivalence point.

Above: A pH curve monitors the changing pH of the analyte. The equivalence point can be determined by identifying the point of inflection. From: https://d20khd7ddkh5ls.cloudfront.net/ph_titration_curve.png

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