Hanna Instruments HI 904, Uick Start Manual, Page: 162 / 180

14
TITRATION THEORY
p
C
l
Figure 3.
Figure 4.
Figure 3 shows a traditional titration curve. The curve is obtained by plotting the pH value
against the volume of NaOH added.
2.2.3 Argentometric Titrations
Argentometric titrations use silver (nitrate) as the titrant and are generally precipitation
titrations, as many silver salts are insoluble. These titrations are commonly used to titrate
and determine the concentration of bromide, chloride, cyanide, iodide, and sulfide.
Argentometric titrations can be done with Mohr’s indicator, when all of the chloride has
reacted, a red silver chromate precipitate is formed or the titration can be easily followed
with a silver ISE (or chloride ISE for chloride titrations) and a reference electrode.
Figure 4 shows the titration of 50 mL of 0.1N NaCl with 0.1N AgNO
3
. The potentiometric
signal is from a chloride ISE, and is plotted as pCl (- log [Cl-]).