(10 points) Student X writes that \"Just because a reaction is spontaneous for o
ID: 554872 • Letter: #
Question
(10 points) Student X writes that "Just because a reaction is spontaneous for one of either the Gibbs or Helmholtz energy, it does not have to be spontaneous for the other one." Professor Old marks this incorrect. Choose if Professor Old is right or wrong by circling your choice and crossing out the alternative. If Professor Old is RIGHT, explain the error in reasoning that cost Student X the points. If Professor Old is WRONG, defend the statement that Student X made. Use no more than seven complete sentences in Standard English. Professor Old is RIGHT Professor Old is WRONGExplanation / Answer
From thermodynamic relation we know the condition of spontaneity as
1. dAT,V£0 where dA is the change in Helmholtz free energy
that means for a process at constant temperature and volume the Helmholtz free energy seeks a minimum. Any spontaneous process in a system at constant T and V must decrease the Helmholtz free energy (if the system is away from equilibrium) or leave the Helmholtz free energy unchanged (if the system is at equilibrium).
2. Similarly for Gibb's free energy the relation is,
dGT,P£0 where dG is the change in Gibb's free energy
That is, at constant T and P the Gibbs free energy seeks a minimum. Any spontaneous process in a system at constant T and P must decrease the Gibbs free energy (if the system is away from equilibrium) or leave the Gibbs free energy unchanged (if the system is at equilibrium).
From the above two relations we see that the conditions for applying Gibb'e free energy for finding spotaneity is different (constant T, P) than for Helmholtz free energy (constant T, V). These two functions are used for two different situations. Hence if a reaction is spontaneous for Gibb'e free energy we can not comment whether it will be spontaneous or non spontaneous for Helmholtz free energy.
Answer is Professor old is right.
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