Edu-Logger 900-230, Руководство пользователя

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14
When the sensor is exposed to CO
2
gas , the
following electrochemical reaction occurs:
Cathodic reaction
:
2Li
+
+ CO
2
+ 1/2O
2
+ 2e
-
= Li
2
CO
3
Anodic reaction
:
2Na
+
+ 1/2O
2
+ 2e
-
= Na
2
O
Overall chemical reaction
:
Li
2
CO
3
+ 2Na
+
= Na
2
O + 2Li
+
+ CO
2
As a result of the electrochemical reaction,
electro-motive force (EMF) would be generated
according to Nernst‟s equation:
EMF = Ec - (R x T) / (2F) ln (P
(CO2)
)
where
P(CO2) : Partial pressure of CO2,
Ec : Constant value R : Gas constant
T : Temperature (K) F : Faraday constant
By monitoring the electromotive force (EMF)
generated between the two electrodes, it is
possible to measure CO
2
.