試題詳解

15. A real gas behaves non-ideally under certain conditions and can be described by the van der Waals equation of state. Which of the following statements best explains the relationship between the compression factor Z, van der Waals' coefficients a and b, and deviations from ideal gas behavior?
(A) For a gas with large a and small b, Z is always greater than 1, indicating the dominance of repulsive forces over attractive forces.
(B) At low pressures, the effect of b dominates, causing Z to decrease below 1 due to volume corrections.
(C) For a gas with large a, Z decreases below 1 at moderate pressures due to the strong attractive interactions between molecules.
(D) At high pressure, the influence of both a and b diminishes, and Z becomes independent of these coefficients, matching ideal gas behavior.
(E) Z is always less than 1 for any gas described by the van der Waals equation, regardless of the values of a and b.