Question

The Gibbs free energy of a mixture of solid A and B ($\alpha$ phase) is given as $\Delta G_{mix} = 10,000 X_A X_B + RT(X_A \ln X_A + X_B \ln X_B)$ (a) When $\Delta H$ is positive, phase separation can occur. The composition range where phase separation occurs is defined by the common tangent rule. Derive an expression for the relationship between $T$ and $X_B$ that defines the composition and temperature range where phase separation occurs. Hint: assume the $\Delta H_{mix}$ versus composition curve is symmetrical in this case. (b) Plot the phase diagram T (y-axis) versus $X_B$ (x-axis) over the temperature range from 300 K < T < 1000 K. (c) Calculate the critical temperature below which a miscibility gap forms.

          The Gibbs free energy of a mixture of solid A and B ($\alpha$ phase) is given as
$\Delta G_{mix} = 10,000 X_A X_B + RT(X_A \ln X_A + X_B \ln X_B)$
(a) When $\Delta H$ is positive, phase separation can occur. The composition range where phase separation occurs is defined by the common tangent rule. Derive an expression for the relationship between $T$ and $X_B$ that defines the composition and temperature range where phase separation occurs. Hint: assume the $\Delta H_{mix}$ versus composition curve is symmetrical in this case.
(b) Plot the phase diagram T (y-axis) versus $X_B$ (x-axis) over the temperature range from 300 K < T < 1000 K.
(c) Calculate the critical temperature below which a miscibility gap forms.

the gibbs free energy of a mixture of solid a and b alpha phase is given as delta gmix 10000 xa xb rtxa ln xa xb ln xb a when delta h is positive phase separation can occur the compos 19499

Added by Amber E.

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