Chapter 3 _________________________________________________________ Ozone Calculation
VAISALA_______________________________________________________________________ 87
06-014
Figure 56
Electrochemical Cell Construction
A chemical reaction starts as soon as ozone (in air) flows into the
cathode solution. The reaction is an iodide-iodine redox reaction. The
current can be measured when the switch S is closed. R is the load
resistance of the circuit.
Ozone Sensor Reactions
The cell system is shown in
are chemically inert, and do not take part in chemical reactions.
Electrochemical reactions take place in the boundary layers of the
electrodes. As soon as air that contains O
3
molecules is bubbled through
the cathode solution, the following total reaction occurs:
2 KI + 0
3
+ H
2
O -> 2 KOH + I
2
+ 0
2
Iodine, I
2
, is formed and the I
2
concentration of the solution starts to
increase. If the external circuit is closed (switch S), reaction 1 is
followed by reactions 2 and 3.
