Question - The SnO₂ -TiO₂ system shows complete solid solution at high temperatures and solvus at lower temperatures. Thermodynamics data indicate that the value of WH is 28.3kJ/mol in the expression for enthalpy of mixing H_mix = x_s x_T WH, where xs is the mole fraction SnO₂ and x_T is the molefraction TiO₂.

1. Culculate H_mix at x_s =0, 0.1, 0.3, 0.5, 0.7 , 0.9 and 1 and plot your values on a graph of H_mix against composition?

2. Calculate the entropy of mixing  at the same compositions and add a curve for -S_mix to your graph  [S_mix = -R[x_sIn x_s+ x_T In x_T] for random mixing of Sn and Ti on their sites].

3. Calculate the gibbs energy of mixing for these compositions at temperatures T of 1550 degrees celucis, 1300 degrees celcous and 1000 degrees celcious .make another graph of these values?

4. From this graph, estimate the compositions of the co-exisisting phases in the two-phase region and hence plot the solvus on a binary phase diagram?