Caveats Thermochemistry And Thermodynamics

Question 1

Enthalpies and free energies

Answer 1

Measured as differences with respect to arbitrary STD state.

Question 2

STD free energy of formation ΣGf•

Answer 2

STD free energy of reaction per mole of substance when substance is formed from elements in most stable forms. Sign reflects how stable product is.

Question 3

Entropies

Answer 3

Defined by comparison to zero entropy level. STD molar entropy is therefore never zero.

Question 4

Factors affecting spontaneity

Answer 4

1. Heat release (not guaranteed)
2. Increase in degrees of freedom (not guaranteed)