Book: KE & R: 20

Question 1

Quantifying entropy in terms of the number of microstates (W) over which the energy of a system can be dispersed.

Answer 1

S = k ln W

Question 2

Quantifying the entropy change in terms of heat absorbed (or released) in a reversible process.

Answer 2

∆S_sys = q_rev / T

Question 3

Stating the second law of thermodynamics for a spontaneous process.

Answer 3

∆S_univ = ∆S_sys + ∆S_surr > 0

Question 4

Calculating the standard entropy of reaction from the standard molar entropies of reactants and products.

Answer 4

∆Sº_rxn = m Σ Sº_products - n Σ Sº_reactants

Question 5

Relating the entropy change in the surroundings to the enthalpy change of the system and the temperature.

Answer 5

∆S_surr = - ∆H_sys / T

Question 6

Expressing the free energy change of the system in terms of its component enthalpy and entropy changes (Gibbs equation).

Answer 6

∆G_sys = ∆H_sys - T ∆S_sys

Question 7

Calculating the standard free energy change from standard enthalpy and entropy changes.

Answer 7

∆Gº_sys = ∆Hº_sys - T ∆Sº_sys

Question 8

Calculating the standard free energy change from the standard free energies of formation.

Answer 8

∆Gº_rxn = m Σ Gº_(f)products - n Σ Gº_(f)reactants

Question 9

Relating the free energy change to the maximum work a system can do.

Answer 9

∆G = w_max

Question 10

Finding the temperature at which a reaction becomes spontaneous.

Answer 10

T = ∆H / ∆S

Question 11

Expressing the free energy change in terms of Q and K.

Answer 11

∆G = RT ln( Q / K ) = RT (ln Q - ln K)

Question 12

Expressing the free energy change with Q and at standard-state conditions.

Answer 12

∆Gº = - RT ln K

Question 13

Expressing the free energy change for nonstandard initial conditions.

Answer 13

∆G = ∆Gº + RT ln Q