Applications of Neutralization Titrations

1

• Applications of Neutralization Titrations
• Standard acid solutions
• HCl(aq) is most common acid reagent
• 0.1 M can be boiled under reflux for 1 hour
  without acid loss
• 0.5 M can be refluxed for 10 min without acid
  loss
• Constant boiling HCl can be weighed and diluted
  to a known volume to prepare standard solutions
  of HCl
• for P between 670 torr and 760 torr
• H2SO4 of HClO4 are usable, but not HNO3
• Standardize using Na2CO3 or (HOCH2)3CNH2 using
  bromocresol green indicator or add measured
  excess of acid and back titrate with OH- with
  known acidbase ratio using phenolphthalein

2

• Applications of Neutralization Titrations
• Standard base solutions
• NaOH most common
• Reasonably stable if protected from air and glass
• Store in polyethylene or parafin coated glass
• Effect of CO2
• CO2 2OH- CO32- H2O
• 1 mol CO2 ? 2 mol OH- ? 2 mol H
• if an indicator with acid color transition is
  used
• CO32 2H H2CO3 no error in base
  consumed
• if an indicator with a base color transition
  is used
• CO32- H HCO3- introduce a
  determinate error

3

• Applications of Neutralization Titrations
• Preparation of NaOH standard solutions
• Purchase 50 NaOH in which Na2CO3 is insoluble
• Pre-prepared solutions are available - Acculute
• Boil the distilled water to remove CO2
• Standardization
• Use potassium biphthalate - molar mass 204
• KH(IO3)2 - a strong acid with molar mass 390
• Kjeldahl determination of N
• Carbonate mixtures