CHEM 111 12.1-12.4

vocab + formulas

spontaneous process:

• occurs naturally under SPECIFIC CONDITIONS

• T dependent!

non-spontaneous process

• does NOT occur naturally under these conditions

direction of spontaneity determined by. . .

1. Enthalpy

2. Entropy

enthalpy

• release of heat promotes spontaneity

• formation of stronger bonds than the ones broken = more spontaneity

entropy (S)

• configurational freedom of a system

• more possible configurations → the state is more probable

microstate

• specific configuration of the locations and energies of the particles in a system

Entropy equation

S = K ln W

S = entropy

k = boltsamnn constant (1.38 × 10^-23) J/K

W = # micro states possible

Relationship between change in S and change in enthalpy

• change of entropy of surroundings is DIRECTLY proportional to change of enthalpy of the system

2nd Law of Thermodynamics:

ALL spontaneous changes = increase in entropy (S) of universe

• ΔSuniverse > 0 for a spontaneous process

• ΔSuniverse < 0 for a nonspontaneous process (spontaneous in the

reverse direction).

• ΔSuniverse = 0 for a process at equilibrium

3rd Law of Thermodynamics:

• The entropy of a pure perfect crystalline substance at zero Kelvin is zero

absolute 0:

0 Kelvins

Standard Entropy

value is for. . .

• 1 mol of a substance at P = 1 bar & T = 298K

• (aq) species at 1M concentration

• calculating standard entropy change of a process