argentometrictitration by talha shah.pptx

argentometric titration

1. Argentometric Titration Talha Shahid

2. The Goal Determine the number of titrant needed to reach the equivalence point of the titration reaction Argentometric is a process of determining the content of a substance based on precipitation reaction from component of the test substance, using precipitation formation of Ag+.

3. Mohr Methods The standard solution is silver nitrate solution using Potassium Chromate indicator. Limited to a solution with a pH value of between 6 and 10. Use : determine the content of Chloride and Bromide. Principle : Using Chromate indicator NaCl + AgNO3  AgCl (precipitate) + NaNO3 2AgNO3 + K2CrO4 (precipitate) + 2KNO3

4. Mohr Methods Titration should be done in neutral or semi-alkalis atmosphere because: In the acid precipitation atmosphere of AgCrO4 will dissolve because the silver dichromate are formed (Ag2Cr2O7) In the silver nitrate base atmosphere will reacted with hydroxide ion to form silver hydroxide precipitation AgNO3 + NaOH  AgOH (precipitation) + NaNO3

5. Mohr Methods The disturbance of this titration: Ion that will precipitate sooner than AgCl, example : F, Br, CNS- Ion that form complex with Ag+, example : CN-, NH3, above pH 7 Ion that form complex with Cl -, example : Hg2+ Cation that precipitate the Chromate, example : Ba2+

6. Volhard Methods Indicator : Fe3+ ( Ferry Ammonium Nitrate) that formed the Red color from the iron (Fe) when it react with SCN-. The materials that used: Standard solution Volume of AgNO3 Ion Halide (X-) example: Cl - Standard Solution Thiocyanat (KSCN or NH4SCN) as a titrant. Indicator iron (III) (Fe 3+ ). The certainty: This titration are occur in Acid condition with pH under 3. If not, the end point can’t be showed.

7. Process: Volhard Methods leftover standard solution of AgNO3 solution which contains halogen ion ,ex : (X-) The excess of ion Ag+ from AgNO3 which not react with Halogen Ion Will Experience The titration With Standard solution of thiocyanate (KSCN or NH4SCN) By using the indicator of Iron (III) (Fe 3+ ). Ag + + Cl   AgCl (s) K sp = 1.82 x 10 -10 titrant #1 white precipitate (excess) Ag + + SCN   AgSCN (s) K sp = 1.1 x 10 -12 titrant #2 white precipitate   Fe 3+ + SCN   FeSCN 2+ K f = 1.4 x 10 +2 indicator red precipitate

8. Fajans Methods Indicator pH indicator of absorption the type of anion and the indicator used.

9. Differences in method