Thermodynamic problems (Pentcho Valev)

Tue Oct 21 03:37:46 EST 1997

In reply to Lukasz Salwinski

Lukasz, I am forced to jump from subject to subject just because you do not
give a concrete answer to any question. Instead, you prefer to hint at my
ignorance - on this forum and in private messages. That's OK - I am rather
used to such things, but still problems should somehow be solved - if
possible, in concrete numbers. So let me repeat the questions - please try
to answer them - only then can the duscussion be fruitful.

1. If the the system

    10 mM KCl                       M                       1 mM KCl

where M is a membrane permeable only to K+, is long enough, what would be
the voltage measured as two microelectrodes reversible for K+ are placed
at the two ends? If, as you say, all possible experiments have already
been done, you can also refer me to the particular paper where the answer
is given.

2. What would be the voltage if the microelectrodes are reversible for Cl-?

3. As we move from the membrane to the right end of the system, how do the
charge density, the field and the potential change? (Again, please refer
me to the particular paper where this description can be found)

4. As the test charge comes from infinity and enters the right end of the
system, what does it meet: a) nonzero charge density b) nonzero field
c) nonzero concentration of some ion d) a combination of some of these

5. What if the initial KCl concentration in the left-hand compartment is
10 mM whereas that in the right-hand compartment is zero? Please try to
describe how the charge density, the field and the potential change
from the membrane to the right, up to infinity. (The potential in the
right-hand compartment cannot be measured since the phase is non-conductive,
but calculations based on thermodynamics show that the potential goes to
infinity with distance. Would you agree?)

6. If the ATP-ADP-P system does  50 KJ/mole work, you should be able to
show the origin of this energy, if you believe in the first law. So please
do this - 50 KJ work is done of which 20 KJ are the internal energy (enthalpy).
Where does the rest (30 KJ) come from?

Of course I do have someting to say about these things, but would like to
know your concrete answers. It used to be too difficult otherwise - I would
present some interpretation, others would comment on my distorted psychology
and insufficient education, and this would continue until everybody got
bored and the discussion ended.

Best regards,

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