Chemistry – Experimental techniques and chemical analysis - Acid-base titrations | e-Consult

Apparatus Required:

• Burette (50.0 cm³)
• 25.0 cm³ volumetric pipette
• Conical flask
• Distilled water
• Indicator (e.g., methyl orange, bromothymol blue)
• White tile
• Stirring rod

Procedure:

1. Carefully pipette 25.0 cm³ of the strong acid solution into a clean conical flask. Rinse the pipette thoroughly with distilled water.
2. Add 2-3 drops of the chosen indicator to the conical flask.
3. Fill the burette with distilled water, ensuring no air bubbles are present. Record the initial burette reading.
4. Slowly add the strong acid from the burette to the conical flask while swirling the flask continuously.
5. Continue adding the acid dropwise until a permanent colour change occurs, indicating the endpoint of the titration.
6. Record the final burette reading.
7. Repeat the titration at least three times to obtain concordant results.

Importance of Multiple Titrations:

Performing multiple titrations is crucial for ensuring accuracy because it helps to reduce the impact of random errors. Each titration may have a slightly different result due to minor variations in the experimental conditions (e.g., slight variations in the amount of indicator added, slight variations in the precision of reading the burette). By taking multiple measurements and averaging them, these random errors are minimised, and a more reliable and accurate result is obtained. The more titrations performed, the more reliable the average concentration will be.