Thermodynamic Property Relations Questions and Answers

Answer: A

The path is constructed so that the only temperature integration happens where heat capacity data apply, that is in the ideal gas state. The residual terms carry the departure at each end and are supplied by an equation of state.

Answer: B

Enthalpy is a state function, so any path between the same two states gives the same difference, and the artificial path is chosen purely for computational convenience. This is the same argument that justifies reversible paths for entropy.

Answer: C

Written as the derivative of Gibbs energy over temperature with respect to temperature, it gives minus enthalpy over temperature squared. It is the standard route from a measured enthalpy of reaction to the temperature dependence of an equilibrium constant.

Answer: D

There is no entropy meter, so the value is built up from calorimetric measurements and latent heats starting from the third law reference. An equation of state then supplies the pressure correction. Absolute entropies are tabulated on exactly this basis.

Answer: A

Correct answer: 1 and 2 only

Statements 1 and 2 are correct: a property change depends only on the end states, which is what makes its differential exact, while heat and work depend on the path and theirs are inexact. Statement 3 has the test the wrong way round - equality of the cross second derivatives is precisely what identifies an *exact* differential, and it is the basis of the Maxwell relations.

Answer: B

A Maxwell relation converts the enthalpy derivative into measurable quantities, giving a coefficient whose sign is decided by whether the expansivity times temperature exceeds one. That is why an ideal gas has a coefficient of exactly zero.

Answer: C

This is precisely their purpose, and it is why a thermodynamic package needs only an equation of state and ideal gas heat capacity correlations. Everything else follows from the relations by differentiation and integration.