Introduction to Titration (College Board AP® Chemistry)

Determine the Concentration of an Analyte

• One of the most important analytical techniques is titration

• Titrations include

  • Acid-base titrations

  • Redox titrations

• The most important glass equipment used in a titration is a burette

• Titrations are used to determine the concentration of a chemical compound in an unknown sample

  • The unknown sample is called the analyte

• The concentration of analyte is determined using a solution of known concentration that is able to react with the analyte

  • The solution of known concentration is called titrant

• The burette is filled with the titrant, while the analyte is placed in a conical flask under the burette

• The endpoint or equivalence point occurs when the moles of titrant have reacted completely with the moles of analyte

  • In most titrations indicator is placed in the analyte solution

  • The indicator is a substance that will change color near the endpoint of the titration

Common titration setup

Titration setup showing the titrant and the analyte. It is a good practice to fill the burette to 0.0 cm³ as shown in the diagram

How to perform a titration?

1. Measure a known volume of analyte and place it into a conical flask

2. Fill the burette with titrant. Remember that the titrant must be a solution of known concentration

3. If necessary, add few drops of indicator in the conical flask

4. Open the tap on the burette carefully and add the analyte portion by portion to the conical flask

   1. After each portion the conical flask must be swirled

5. As you start getting near the endpoint, the portions should be added dropwise

6. Close the burette tap when one drop has caused a permanent color change

7. Record the volume of titrant used for the equivalence point. This volume will be used to determine the concentration of analyte

Determining the concentration of analyte

• One of the most assessed calculations in AP Chemistry regarding titrations is determining the amount of analyte

• The steps for this calculation are summarized in the following diagram

Steps for determining the concentration of analyte

General steps that must be followed to determine the concentration of analyte using the volume recorded from the equivalence point of the titration