Dear Colleagues,
I would like you to help me solve a few thermodynamic paradoxes. I have
been trying to discuss them with people for many years, but as my claims
question ultimately the validity of the second law... you can imagine what the
reaction was.
Ten days ago I posted some of them in the bio-info group, so you can see
them there. Let me present here the briefest one.
Let the ATP-ADP-Pi system do work on another system, e.g. driving the
reaction M = N:
ATP + M = ADP + Pi + N /1/
Obviously the enthalpy of the reaction is equal to the sum of the enthalpies
of ATP hydrolysis and M = N, and this relation is independent of both
the concentrations and the distance from equilibrium:
delta H = delta H(ATP = ADP + Pi) + delta H(M = N) /2/
However note that delta H(M = N) is in fact the energy the second system
receives, i.e. it can be conceived as work, W, done on it. Hence
W = delta H(M = N) = delta H - delta H(ATP = ADP + Pi) /3/
It follows that the work done on the second system is independent of both
the concentrations and the distance from equilibrium, insofar as the
enthalpies are, according to the first law, independent.
On the other hand, if the reaction /1/ is close to equilibrium, the
second law predicts that
W = -delta G(ATP =ADP + Pi) = -delta Go - RTln((ADP)(Pi)/(ATP)) /4/
i.e. W does depend on the concentrations.
It seems to me that /3/ and /4/ are incompatible. What do you think?
Pentcho Valev
State Commission of Varieties
125 Tzarigradsko Chaussee, Block 1
1113 Sofia, Bulgaria
E-mail: rumym at bgearn.acad.bg
