Thermodynamic problems (Pentcho Valev)

RUMYM at BGEARN.ACAD.BG RUMYM at BGEARN.ACAD.BG
Thu Oct 23 04:37:11 EST 1997


In reply to Lukasz Salwinski

>   However you are wrong that the potential depends on the ratio of the   <
>compartments. The only thermodynamic requirement is that the              <
>electrochemical potential                                                 <
>
>     MU(elchm) = MUo + RTln(C_K+) + F(Phi)                 /1/            <

>where C_K+ is the concentration of K+, F is the Faraday and Phi is the    <
>electrical potential, be uniform throughout the system. As C_K+ goes      <
>to zero with distance to the right, it follows unequivocally from /1/ that<

it does not universally go to zero. sorry :o( whatever the bulk concentration of
K+ is                                                                       <
going to be depends on the ratio of the reservoirs' volumes and membrane    <
capacitance.                                                                <

>Phi goes to infinity.                                                      <

nope.                                                                       <

Lukasz, please say something concrete after all| If the K+ concentration
does not go to zero far to the right from the membrane, what does it do?
Does is at least decrease (then the potential must increase)? Does it
approach some finite value? If, in a thought experiment, the system gets
longer and longer, how will the K+ concentration at the right end change
(of course, each time  equilibrium is established)?
   Thermodynamics has offered no way of its own verification - it has left
this task to the opponents. Sometimes I even have the feeling that
verification is forbidden, like in any other dogmatic system.

Pentcho



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