Page 89 - PC 101 Interactive practical book
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MANSOURA NATIONAL UNIVERSIY
         PHARM D- CLINICAL PHARMACY                        LEVEL I                        PHARM. ANAL. CHEM. I (PC 101)











                      Volhard method   Cl -  , Br - , I -  & SCN - .   Back (Residual) titration.    1 st  standard (25 ml):  AgNO3.   2 nd  standard (titrant): NH4SCN or KSCN.   Acidic medium (HNO3).   Ferric alum = Ferric ammonium Sulfate   { FeNH4(SO4)2.12H2O }.  OR  2) Ferric nitrate { Fe(NO3)3 }.   Faint orange or faint red color.
















                                                                           1)












                      Mohr's method   Cl -  , Br -  (Not for I -  or SCN - ).   Direct titration.   Standard AgNO3.   Neutral or slightly alkaline. (pH ≈ 6.5 -9).   1 ml of 5% Pot. Chromate (K2CrO4) solution.   First permanent darkening of the yellow chromate color  [due to the formation of Ag2CrO4 (brick red ppt) at the  end point leading to darkening of the solution].




























                               Sample                                                              E.P color change

                                         Type of titration   Standard Solutions   pH   Indicator











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