6.10 For two species, A and B, with a positive enthalpy change of

6.10 For two species, A and B, with a positive enthalpy change of mixing:
(a) Are the like interactions or the unlike interactions stronger? Explain.
(b) If pure species A and B are mixed adiabatically, will the temperature (increase, stay the same,
decrease, or cannot tell)? Explain.
(c) If pure species A and B are mixed isothermally, what will be the sign of Q? Explain.
(d) If an equamolar mixture of species A and B is mixed adiabatically with pure A, will the
temperature (increase, stay the same, or decrease)? Explain.
6.48 Enthalpies of mixing for binary mixtures of cadmium (Cd) and tin (Sn) have been fit to the
following equation at 500°C:
hmix  13,000 X Cd X Sn [ J mol]
where, XCd and XSn are the cadmium and tin mole fractions, respectively. Consider a mixture of
3 moles Cd and 2 moles Sn.
(a) Show that:
 H 
mix
Cd
 H Cd  hCd
(b) Based on the equations above, calculate values for H Cd  hCd and HSn  hSn at 500°C.
(c) Show that the results are consistent with the Gibbs–Duhem equation.
(d) Data from which the above equation was derived are presented below, along with the model
fit. Graphically determine values for H Cd  hCd and HSn  hSn at 500°C. Compare your answer to
part (b). Show your work.

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