Fundamentals of Analytical Chemistry: Titrations in Analytical Chemistry

Chapter Objectives

  • Determine an analyte using volumetric titrations.
  • Understand advantages and disadvantages of gravimetric titrations.
  • Prepare and standardize a solution.
  • Define and use back-titrations.
  • Minimize titration errors.
  • Differentiate between endpoint and equivalence point.
  • Utilize chemical indicators.
  • Work with primary and secondary standards.
  • Calculate volumetric titrations.
  • Construct sigmoidal and linear segment titration curves.

Key Concepts

  • Titration Methods
    • Measure the quantity of a reagent to react with analyte.
    • Volumetric Titrations: Measure volume of standard reagent.
    • Gravimetric Titrations: Measure mass of reagent.
    • Coulometric Titrations: Measure charge.
  • Types of Titrations: Redox titrations, amperometric, and spectrophotometric.

Important Definitions

  • Standard Solution: Known concentration reagent added to analyze.
  • Back-Titration: Determine excess reagent amount by titrating with another solution.
  • Equivalence Point: Amount of reagent equals analyte.
  • End Point: Physical change indicating equivalence.
  • Primary Standard: High purity, stable compound (e.g., NaCl).
  • Secondary Standard: Purity determined by analysis.

Titration Error

  • Et = V{ep} - V_{eq}
    • V_{ep}: Volume at endpoint
    • V_{eq}: Theoretical volume at equivalence point.

Standard Solutions

  • Ideal characteristics: Stability, rapid reaction, complete reaction, selective.
  • Establishing Concentrations:
    • Direct Method: Known mass of primary standard.
    • Standardization: Titrate against standard to find concentration.

Volumetric Calculations

  • Concentration Expressions: Molar (moles/L), Normal (equivalents/L).
  • Key Equations:
    • ext{mass}A = ext{amount}A imes ext{molar mass}_A
    • ext{amount}A = rac{ ext{mass}A}{ ext{molar mass}_A}
    • ext{amount}_A = V imes c (for volume)

Titration Data Calculation

  • Use stoichiometric relationships to calculate analyte concentration based on titrant volume and concentration.