3. Chloride Methods  Gravimetric Chloride  Potentiometric titration  Visual Indicators  Mohr Method  Fajans Method  Volhard Method

4. In all of these methods the chloride sample is dissolved & reacted with silver nitrate Cl -1 + Ag +1  AgCl

5. Gravimetric Chloride Use a balance to measure mass of sample and AgCl Precipitate No endpoint detection

6. Potentiometric Titration Balance for mass of sample Buret for volume of titrant added pH meter with silver electrode for end-point detection

7. Mohr Method Balance for mass of sample Buret for volume of titrant added Indicator for endpoint detection Na 2 CrO 4

8. Mohr Method Cl -1 + Ag +1  AgCl Ksp =1.82 x 10 -10 CrO 4 -2 + 2Ag +1  Ag 2 CrO 4 (brick red) Ksp = 1.2 x 10 -12 Must titrate a blank and subtract from total volume of silver nitrate added

9. Fajans Method Balance for mass of sample Buret for volume of titrant added Indicator for endpoint detection Fluorescein- Adsorption Indicator

10. Fajans Method Fluorescein

11. Fajans Method HFl  H +1 + Fl -1 (yellow green)

12. Fajans Method Cl -1 + Ag +1  AgCl Chloride titrated with silver nitrate AgCl Cl -1 AgCl Ag +1 Colloidal ppt Before eq pt AgFl Red Color

13. Volhard Method Indirect Method – Back titrate excess Ag +1 Add excess silver nitrate Ag +1 + Cl -1  AgCl (s) (white ppt) + Ag +1 Excess Ag +1 is titrated with standard with standard potassium thiocyanate. SCN -1 + Ag +1  AgSCN (s) Fe +3 indicator Fe+3 + SCN -1  Fe(SCN) +2 (red ppt)