Titration Methods: pH-metric and Conductimetric
This page introduces two important titration techniques: pH-metric and conductimetric titrations. These methods are crucial for quantitative chemical analysis and determining unknown concentrations of solutions.
pH-metric Titration
pH-metric titration is based on monitoring the pH changes during an acid-base reaction. The setup includes a burette containing the titrant (known concentration) and a beaker with the solution to be analyzed.
Definition: The equivalence point of a titration is reached when the reactants are in stoichiometric proportions, and both reactants are completely consumed.
The titration curve (pH vs. volume added) shows a sharp jump at the equivalence point. This point can be determined using:
- Tangent method
- Derivative method
Example: For a reaction aA + bB → cC + dD, at equivalence: C_A * V_0 = (b/a) * C_B * V_E
Where C_A and C_B are concentrations, V_0 is initial volume, and V_E is volume at equivalence.
Conductimetric Titration
Conductimetric titration relies on measuring the electrical conductivity of the solution during the titration process.
Vocabulary: Conductivity (σ) is related to ion concentration by σ = λ * [X^z], where λ is molar conductivity and [X^z] is ion concentration.
The titration curve (conductivity vs. volume added) shows distinct changes in slope before and after the equivalence point.
Example: In titrating barium chloride with sodium sulfate, the conductivity changes are due to the replacement of Ba^2+ ions with Na+ ions.
Highlight: The equivalence point in conductimetric titration is determined by the intersection of the conductivity slopes before and after the reaction completion.
The page includes diagrams illustrating the setups for both titration methods and graphical representations of the titration curves, enhancing understanding of these analytical techniques.
