L1 /
10
CH3041
COMBINATION
ELECTRODE
1) Combination
electrode Glass electrode.
The ‘classic’
pH electrode is a combination
electrode where the glass electrode (0.1 M HCl) is in the same holder as a reference
Ag |AgCl electrode.
electrode where the glass electrode (0.1 M HCl) is in the same holder as a reference
Ag |AgCl electrode.
-
• The ion
selectivity arises as the
H+ ion replaces Na+ in the glass
cation exchange sites. These Na+
migrate slowly to the other side.
H+ ion replaces Na+ in the glass
cation exchange sites. These Na+
migrate slowly to the other side.
• R » 108 W so very
little
current flows.
current flows.
• precision +/-
0.01pH
V
Reference
Ag/AgCl
Ag/AgCl
Electrolyte
Glass membrane
Working
Ag/AgCl
Ag/AgCl
Salt bridge
