Which of the following statements is true?
A. The excess molar enthalpy for a system behaving according to the ideal solution model will always be equal to one, regardless of the composition of the mixture.
B. Temperature, pressure and mole fraction are all intensive variables.
C. According to the Gibbs phase rule, a two-component liquid mixture will have one degree of freedom.
D. All of the above are true.
E. None of the above are true.
A. Incorrect. Review Section 9.3. The excess molar enthalpy will be zero for an ideal mixture.
B. Correct. Each of these can be specified without making any reference to the amount of mass or moles present in the system.
C. Incorrect. Note that we have not stated that temperature and pressure are fixed, only that there is one phase and two components. Applying the Gibbs phase rule for C = 2, ? = 1; F = 2 – 1 + 2 = 3. We can specify temperature, pressure and a third intensive variable to fix this system.
D. Incorrect. At least one is wrong.
E. Incorrect. At least one is true.
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Figure 41-7
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