ANALYSISLAB | ASSAY OF AMMONIUM CHLORIDE

• Method used:

  Argentometric titration(back titration)

  or Volhard's Method (involves silver ions)
• Primary Standard: Potassium Thiocyanate (KSCN)(Analyte)
• Secondary Standard: Silver Nitrate (AgNO3) (Analyte)
• Indicator: Ferric Alum (NH4Fe(SO4)2)
• Steps:

  1. Preparation of Silver Nitrate
  2. Preparation of Potassium Thiocyanate2b. Standardization of Potassium Thiocyanate
• Volhard's Method

  • By Jacob Volhard 1874
  • Indirect Titration/Back Titration
  • 2 Stage Analytical Technique where filtering is involved
  • Reactant A of unknown concentration is reacted with excess reactant B of known concentration.
  • Direct Titration is then performed to determine amount of reactant B in excess.
• Standardization of KSCN

  -Analyte: Silver Nitrate

  -Titrant: Potassium Thiocyanate

  -Indicator: Ferric Alum

  Goal: Determine concentration of silver nitrate
• Assay of ammonium chloride

  -Endpoint: Flesh Endpoint

  -Titrant: Silver Nitrate

  -Indicator: Ferric Alum

  *Titrate AgNO3 with KSCN, then wash ppt with distilled water.
• Uses of Indirect Titration

  • One of the reactants is volatile
  • Acid/Base is an insoluble salt
• Balanced Equations

  Ag + CL -> AgCl

  Ag + SCN -> AgSCN

  SCN- + Fe3 -> FeSCN