Titrations

Science

Definition

A laboratory technique used to determine the unknown concentration of a solution by gradually adding a solution of known concentration until the reaction reaches its equivalence point. An indicator or pH meter signals when the reaction is complete.

How It Works

  1. Fill a buret with the titrant (solution of known concentration).
  2. Measure a precise volume of the analyte (unknown solution) into a flask and add an indicator.
  3. Slowly add titrant to the analyte while swirling the flask.
  4. Watch for the color change indicating the endpoint has been reached.
  5. Record the volume of titrant used and calculate the unknown concentration using M₁V₁ = M₂V₂.

Examples

  • Using NaOH to titrate an unknown concentration of HCl with phenolphthalein as the indicator
  • Determining the acetic acid concentration in a vinegar sample
  • Titrating a water sample to measure its hardness (calcium content)
Key Fact

At the equivalence point: M₁V₁ = M₂V₂ (for 1:1 acid-base reactions).

Related Terms

Acid-base theory Neutralization reactions Ph calculations Concentration

Study This Concept

Practice titrations with free review games in these units:

AP Chemistry Unit 8: Acids and Bases