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

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

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

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

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

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

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

Fajans Method Fluorescein

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

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

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)