Candidates must be familiar with use of the technique of volumetric analysis, including:

• preparing a standard solution

  A solution of accurately known concentration is known as a standard solution.

  A standard solution can be prepared by

  • weighing a primary standard accurately
  • dissolving in a small volume of solvent (usually deionised or distilled water) in a beaker
  • transferring the solution and rinsings into a volumetric flask, of an appropriate standard volume
  • making up to the graduation mark with solvent
  • stoppering and inverting

• accurate dilution

  Standard solutions can also be prepared by accurate dilution by

  • pipetting an appropriate volume of a standard solution into a volumetric flask
  • making up to the graduation mark with solvent
  • stoppering and inverting

• standardising solutions to determine accurate concentration

• titrating to obtain concordancy using burettes, pipettes and volumetric flasks

• choosing an appropriate indicator

A primary standard is a substance which is readily available and must have the following characteristics

• be available in a high state of purity
• be stable when solid and in solution
• be soluble
• have a reasonably high $GFM$

Examples of primary standards include

• sodium carbonate, $Na_2CO_3$ → for acid/base titrations
• hydrated oxalic acid, $H_2C_2O_4 \space · \space 2H_2O$ → for acid/base titrations
• potassium iodate, $KIO_3$ → for redox titrations
• ethylenediaminetetraacetic acid, $EDTA$ → for complexometric titrations
• silver nitrate, $AgNO_3$
• potassium hydrogen phthalate, $KH(C_8H_4O_4)$
• potassium dichromate, $K_2 Cr_2O_7$

Sodium hydroxide is not a primary standard as it has a relatively low $GFM$, is unstable as a solid (absorbs moisture) and unstable as a solution. Sodium hydroxide solution must be standardised before being used in volumetric analysis.