Volumetric analysis

• What technique is used for volumetric analysis?

  Volumetric analysis technique
• What are the steps involved in preparing a standard solution?

  1. Weigh a primary standard accurately
  2. Dissolve in a small volume of solvent
  3. Transfer to a volumetric flask
  4. Make up to the graduation mark with solvent
  5. Stopper and invert
• What is a solution of accurately known concentration called?

  Standard solution
• How can standard solutions be prepared by dilution?

  Pipetting a standard solution into a volumetric flask
• What must a primary standard be available in?

  High state of purity
• What are the characteristics of a primary standard?

  Stable, soluble, and high GFM
• What are examples of primary standards?

  • Sodium carbonate, Na2CO3
  • Hydrated oxalic acid, H2C2O4 · 2H2O
  • Potassium hydrogen phthalate, KH(C8H4O4)
  • Silver nitrate, AgNO3
  • Potassium iodate, KIO3
  • Potassium dichromate, K2Cr2O7
• Why is sodium hydroxide not a primary standard?

  It has low GFM and is unstable
• What must sodium hydroxide solution undergo before use?

  Standardisation
• What type of titrations am I familiar with?

  Acid-base titrations
• What are redox titrations based on?

  Reactions between oxidising and reducing agents
• What is EDTA used for in complexometric titrations?

  To determine concentration of metal ions
• What is the purpose of back titrations?

  To find moles of a substance using excess reactant
• How is the number of moles determined in a back titration?

  By titrating the excess reactant
• Why is back titration useful for low solubility solids?

  It helps determine quantity of insoluble substances
• What is the process of standardising sodium hydroxide solution?

  1. Prepare a standard solution of primary standard
  2. Titrate sodium hydroxide against the standard solution
  3. Calculate the concentration of sodium hydroxide
• Why are reactants added in excess sometimes?

  To ensure that all the molecules in the other substance have reacted