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Introduction:
The objective of this experiment is to determine the factor RT/F from
diffusion potential by using a permeable membrane and to determine the transport
numbers using a cellophane membrane.
If we have two electrolytes separated by a membrane an electric potential difference
will be generated and ions will move from high concentration to the low one. This
potential energy will be as follows:
∆φ
= (RT/zF) ln (C1/C2)
∆φ
D
= (t_ 
t+ ) =
∆φ
In this experiment two parts will be discussed :
Part I:
Here we have the membrane that separate the electrolytes allow only cations
to pass. The following equations will be got:
∆φ
D
= RT/zF
ln(a2/a1)
therefore plotting
∆φ
D
vs. ln(a1/a2) will give us a slope equals RT/zF. Note that we
have replaced the concentration by the activity which is more real.
Part II:
The membrane used allows both ions to pass from the concentrated side to the
low one and we got the following equation:
2t_  1
= zF
∆φ
D
/ RT ln(a1/a2)
Procedure:
Look at the experiment book in pages:4951
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This note was uploaded on 04/13/2011 for the course CHEM 311 taught by Professor Alialhabib during the Fall '09 term at King Fahd University of Petroleum & Minerals.
 Fall '09
 AliAlHabib
 Chemistry, pH

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