Titration is a widely used technique for determining the concentration of an unknown solution when the concentration of another solution is known. One of the most common types of titration is an acid-base titration.
In this technique, a carefully measured volume of the known acid/alkali is placed into a conical flask and a solution of unknown concentration is slowly added to it until the reaction is complete.
To determine when the reaction is complete, we often use an indicator, which changes colour to signal the endpoint of the reaction.
To perform an acid-base titration, you will need:
Let’s go through the steps involved in carrying out a titration:
1. Use the pipette to transfer a precise volume of alkali to a clean conical flask.
2. Add a few drops of indicator to the conical flask.
3. Fill the burette with the acid and record the initial volume reading.
4. Slowly add the acid from the burette to the alkali in the conical flask. After this, swirl the conical flask to ensure it is mixed thoroughly.
5. As you approach the endpoint of the reaction, add the acid drop by drop until you reach the endpoint.
6. Record the final volume reading on the burette.
7. Repeat steps 1-6 until you get concordant titres.
After completing the titration, it is important to record your results accurately. Here is an example of a table for recording results:
|Run||Final reading (cm³)||Initial reading (cm³)||Titre (cm³)|
In this table, the ‘run’ refers to the trial number, and the ‘final reading’ and ‘initial reading’ refer to the volume of the titrant (the known solution) dispensed from the burette at the start and end of the titration, respectively. The ‘titre’ is the difference between the final and initial readings.
Once you have recorded your results in a table like this, you can calculate the mean titre by adding up the titre values and dividing by the number of concordant titres obtained.