The thermodynamics of dissolving

We now have enough information to formulate a thermodynamic description of dissolving to form an ideal solution. As we see in the following Justification, when an amount Ug of a solute B dissolves in an amount of a solvent A at a temperature T, 

31 The variation of the Gibbs energy of dissolving with composition for two components at constant temperature and pressure. Note that AG 0 for all compositions, which indicates that two components mix spontaneously in aU proportions. 

The Gibbs energy of the two unmixed components is the sum of their individual Gibbs energies  

When B is dissolved in A to form an ideal solution, the Gibbs energy becomes 

Equation 3.20 tells us the change in Gibbs energy when a solute dissolves to give an ideal solution (Fig. 3.31). The crucial feature is that because x and Xb are both less than 1, the two logarithms are negative (Inx 0 if x 1), so AG 0 at all compositions. Therefore, dissolving to form an ideal solution is spontaneous in all proportions. Furthermore, if we compare eqn 3.20 with AG = AH — TAS, we can conclude that  

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The thermodynamics of dissolved apolar polymer systems is usually described by the Hory-Huggins theory [43-45]. The Flory-Huggins theory is based on the so called mean field approach which is a theory that assumes, that each part of the monomer-monomer interaction and solvent-solvent interaction has the same... 

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