Three E’s Of Thermodynamics

Question 1

Analysis of free energy changes for chemical reactions occur at?

Answer 1

Constant temperature and constant pressure

Question 2

Reversible chemical reaction?

Answer 2

Forward-spontaneous = product-favored
Reverse-spontaneous = reactant-favored

Question 3

What is spontaneous change?

Answer 3

A change that occurs without external influence
It does not need to be fast!

Question 4

Free Energy of Reaction ΔGrxn

Answer 4

Units: J/mol or kJ/mol
Net change in free energy that accompanies chemical reaction at constant T and P

Question 5

Enthalpy of Reaction ΔHrxn

Answer 5

Units: J/mol or kJ/mol
Net heat energy absorbed or released as result of chemical reaction at constant P

Question 6

Entropy of Reaction ΔSrxn

Answer 6

Units: J/mol or kJ/mol
Net change in degrees of freedom or extent of randomness as result of chemical rxn at constant T

Question 7

First Law of Thermodynamics

Answer 7

ΔU = q + w
ΔU : Change in internal energy of system
Energy is conserved

Question 8

Second Law of Thermodynamics

Answer 8

Entropy of universe increases for spontaneous processes. Lower degrees of freedom to higher degrees of freedom

Question 9

Third Law of Thermodynamics

Answer 9

Entropy of perfect crystal approaches zero (S -> 0) as absolute temperature approaches zero
As temperature of substance is raised from absolute zero, more spatial orientations become available and thermal disorder increases.

Question 10

Perfect crystal

Answer 10

Substance in which all atoms are in perfectly ordered array with no positional disorder

Question 11

T -> 0

Answer 11

Absence of thermal motion and absence of thermal disorder