Ionode IJ pH V5.1 - Manual (Page 9)

Ionode IJ Instruction Manual 9
Unequal concentrations of H
+
on either side of
the membrane cause the system to equalise
the number of positive ions on either side of the
membrane. This causes migration of a lithium
ion through the membrane (see Figure 8).
As the negatively charged oxygen counter ions
are fixed in the glass structure, a potential
develops across the membrane (see Figure 9).
This builds until the charge developed opposes
further migration according to the Nernst
equation.
Li
+
H
+
Si
O
-
O
-
O
O
-
O O
-
Si
H
+
Li
+
H
+
Li
+
H
+
H
+
Cl
-
Cl
-
Li
+
Figure 9
H
+
Li
+
H
+
Si
O
-
O
-
O
O
-
O O
-
Si
H
+
Li
+
H
+
Li
+
H
+
H
+
Cl
-
Cl
-
Li
+
Figure 8