Pg:- 117,118 Ch:- 5

#chemistry #mole #titration

• Titration is a laboratory technique used in chemistry to determine the concentration of an unknown solution by reacting it with a solution of known concentration, called the titrant. This method is commonly used in acid-base reactions but can also be applied to redox reactions, precipitation reactions, and complexometric titrations.

Procedure:

• Setup:

  • A burette is filled with the titrant (solution of known concentration).

  • The analyte (solution of unknown concentration) is placed in a flask, often with an indicator that changes color at the equivalence point.

• Procedure:

  • The titrant is slowly added to the analyte while the solution is stirred.

  • The addition continues until the reaction reaches the equivalence point, where the amount of titrant is stoichiometrically equivalent to the amount of analyte. At this point, the indicator changes color, signaling that the titration is complete.

• Equivalence Point:

  • The equivalence point is where the moles of titrant equal the moles of analyte, according to the balanced chemical equation. This point is crucial for calculating the concentration of the unknown solution.

• End Point:

  • The end point of a titration is indicated by a noticeable change in the system, such as a color change due to the indicator. Ideally, the end point should coincide with the equivalence point.

Types:

• Acid-Base Titration:

  • Used to determine the concentration of an acid or base. The titrant is usually a strong acid or base, and the indicator is chosen based on the expected pH at the equivalence point (e.g., phenolphthalein for strong acid-strong base titrations).

• Redox Titration:

  • Involves a redox reaction where the titrant and analyte undergo an oxidation-reduction process. Potassium permanganate (KMnO₄) is a common titrant used in redox titrations.

• Precipitation Titration:

  • Relies on the formation of a precipitate during the reaction between the titrant and the analyte. For example, silver nitrate (AgNO₃) can be used to determine the concentration of chloride ions by forming a precipitate of silver chloride (AgCl).

• Complexometric Titration:

  • Used to determine concentrations of metal ions through the formation of a complex. Ethylenediaminetetraacetic acid (EDTA) is a common titrant in this type of titration.