Accurate Determination of the End-Point of Titrations

Section 1: End-Point of Titrations

End-Point of a Titration: The point in the titration process where the reaction between the titrant and the analyte is complete, indicated by a change in colour due to the indicator added.
Colour Change: During a titration, the indicator used changes colour, signifying the end-point. This shift marks the exact moment when all the analyte has reacted with the titrant.
Selection of Indicator: Choosing the correct indicator is crucial because different indicators change colour at different pH levels. The indicator should match the pH at the equivalence point of the titration.

Section 2: Judging the End-point

Colour Consistency: The end-point has been reached when the colour change remains consistent after swirling. This might take a drop or two beyond the initial hint of a colour change, indicating that the solution has adequate titrant.
Overshooting the End-point: If too much titrant is added, the solution could go past the end-point, and the titration would have to be repeated. This is known as overshooting and should be avoided.
End-Point Recognition: Rapid addition of titrant can be done initially, but the titrant should be added dropwise as the end-point nears to ensure accurate determination.

Section 3: Achieving Accuracy

Repetition of Titration: To ensure accuracy of results, the titration process should be repeated several times. The mean titre is then calculated from consistent results, excluding any anomalies.
Noting Measurements: Precisely note down volume readings from the burette at the beginning and end of the titration to calculate the volume of titrant used.
Instrument Calibration: Burettes used in titration should be regularly checked and calibrated to ensure accurate measurements.

Section 4: Errors and Corrections in Titration

Parallax Errors: These occur when the measurement scale is not viewed from straight ahead. Ensure the meniscus of the liquid in the burette is at eye level when reading the volume.
Recording Errors: Mistakes while noting down the initial and final readings could lead to big variations in results. Double-check readings before recording.
Handling Errors: Mishandling of apparatus, especially while dispensing drops towards the end-point can result in inaccurate results. Therefore, exercise care while conducting the experiment.