12. There are two vessels isolated from the external environment. One contains n1 mol of solid, n2 mol of liquid A at the melting point, the other contains n1 mol of solid and n2 mol of liquid B at the melting point. Both vessels are brought into contact. Determine in which direction the process will take place in the system; which substance - A or B - will melt or solidify. Under what conditions will the system come to equilibrium (T, n1, n2)? Calculate the change in the entropy of the system during the transition from the initial state to the equilibrium state. Is this process reversible or irreversible? For the calculation, use the following data and reference [S.Kh.].

N options Substance n1 n2
A B
12 C3H5(OH)3 p-C6H3(CH3)2 0.2 0.8

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