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Chemistry / How does chemosynthesis generate energy?
« on: 09/06/2011 10:02:56 »
Whether a reaction happens spontaneously (all by itself)is a function of its change in Gibbs' free energy, not enthalpy. While enthalpy is a part of Gibbs' free energy, so is the change in entropy. There is another consideration on spontaneity that is not addressed when calculating energy from standard states: the concentration ("activity") of each of the species involved in the reaction. This is a sort of hidden aspect to "standard state or standard conditions". This would mean that for your calculation to represent the actual value found for energy changes in the real system, a cell wold have to be in a gas whose pressure of CO2 gas and H2S gas would each need to be about 1 atmosphere. I hope this helps.