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A titration is a technique used (by analytical chemists) to determine the unknown concentration of a solution accurately. This is done by reacting it with a 'standard solution' of accurately known concentration and measuring the volumes of each solution required. This requires good practical technique and precision.

Carrying out a titration

This short video clip shows the correct way to carry out a titration, from setting up and filling a burette to using it accurately. It includes the correct technique for using a volumetric pipette and a burette.

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Points to consider:

Why is it preferable to allow the solution from the pipette to run into the flask by releasing it to run under gravity and touching the pipette onto the dispensed solution below it or the side of the flask?

This method will ensure that the correct volume of solution is dispensed, leaving behind any drops that are already accounted for in the calibration of the pipette, rather than risking knocking out this extra amount, which would adversely affect the calculations.

A funnel is used to fill the burette. Why is it removed before starting the titration?

The funnel should always be removed in case a drop of solution from the funnel runs down into the burette during the titration – this would alter the reading of the volume.

Is the white tile under the conical flask essential?

It doesn't have to be a tile, but a white background is very helpful in determining when there is a permanent colour change and the titration is finished as this can be tricky to see.

In the video, what is meant by repeating the titration until 'concordant results' are achieved?

This means obtaining two titres (volumes) that are very close together. This means typically within 0.1 cm³ of each other, so that the average of the two titres is used in the calculations.

When might it be correct to blow out the solution from a pipette completely?

There are two common types of graduated pipette (pipette showing increments of volume) used to measure and transfer various amounts of liquid. These are Mohr pipettes (requiring drain-out) and serological 'blowout' pipettes that don't have zero marks at the tip. Blowing out the solution from this graduated pipette is the correct technique, as it's designed to transfer various amounts of liquid that are measured right to the tip. These pipettes are normally marked by a coloured or etched band at the top of the pipette.