Energy of Spontaneous Processes

In order to provoke spontaneous processes, we will introduce into the solution some amoimt of heat Q, i.e., we will increase the kinetic energy of its components. Under conditions of isolation and constancy of the ambient pressure part of this excess energy will go for the increase of the solution volume by AV values. Therefore, part of the heat will come back in the form of mechanical work (expansion work) 

The rest of the acquired energy Q is expended for the change of the internal energy of the solution by At/ value. The internal energy, according to the molecular-kinetic theory, is the sum of the internal kinetic energy of molecules chaotic motion and atoms, and potential energy of their balanced interaction forces. Therefore, under the first law of thermodynamics we have 

Then the useful work of spontaneous chemical reactions in a solution is determined from the equation 

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