By Claire Gillespie, Updated Mar 24, 2022

In analytical chemistry, a titration is a quantitative technique where a solution of known concentration (the titrant) is added to a measured volume of another solution of unknown concentration (the analyte). The process continues until the reaction between the two solutions is complete. At this moment, called the equivalence point, the number of moles of titrant equals the number of moles of analyte, allowing you to calculate the analyte’s concentration with precision.

TL;DR

The equivalence point is reached when the reacting species are stoichiometrically balanced. It is detected by a clear change in an indicator or a plateau on a pH meter, indicating no further reaction.

Types of Titration

• Acid‑base titrations – neutralization of an acid by a base or vice versa, commonly monitored with a color indicator or pH meter.
• Redox titrations – transfer of electrons between species, often using an oxidizing or reducing agent as the titrant.
• Complexometric titrations – formation of a stable complex between the analyte and a ligand, useful for metal ion analysis.
• Precipitation titrations – a precipitate forms at the equivalence point, such as in the titration of a chloride ion with silver nitrate.

Essential Equipment

• Erlenmeyer flask or beaker (preferably 250 mL)
• Precise burette (0.01 mL resolution) and stand
• Analytical balance for measuring solids
• Distilled water and pipette for dilution
• Indicator solution (e.g., phenolphthalein, methyl orange) or a calibrated pH meter
• Glassware for rinsing solids into solution

Step‑by‑Step Procedure

1. Weigh or measure the analyte accurately and transfer it into the flask. If the analyte is solid, rinse it into the flask with distilled water.
2. Add distilled water until the analyte is fully dissolved, then record the final volume.
3. If using a color indicator, add a few drops and swirl gently to mix.
4. Fill the burette with the titrant, ensuring no air bubbles, and record the initial volume.
5. Place the flask under the burette, close the tap, and begin adding the titrant dropwise.
6. After each addition, swirl the flask to ensure complete mixing.
7. Continue adding the titrant until the indicator changes color and stays that way, or until the pH meter shows a plateau indicating the equivalence point.
8. Record the final burette reading. The difference between initial and final volumes, multiplied by the titrant concentration, equals the moles of analyte.
9. Use the moles of analyte and the known volume of the analyte solution to calculate its concentration.

For greater accuracy, perform at least two titrations and average the results. Always calibrate your burette before each run, and keep the burette tip clean and free from drips.

By following these best practices, you can confidently locate the equivalence point and determine concentrations with the precision required for rigorous chemical analysis.