Spontaneity

Enthalpy

heat absorbed by a system during constant pressure process

• plays a role in determining whether process is spontaneous

Entropy

Measure of randomness in a system

• plays a role in determining whether a process is spontaneous

Spontaneous Process

Done without intervention

• Spontaneous in one direction becomes nonspontaneous in reverse direction

• Can be slow and fast reactions

Reversible process

System changes so system & surroundings can return to original state. Maximizes work done ON surroundings

Irreversible Process

cannot be undone by reversing the change to the system or cannot have process exactly followed in reverse.

Spontaneous processes are..

Irreversible

Second law of Thermodynamics

Entropy of universe increases in any spontaneous processes

Reversible process relationship

Δ H = change in..

Enthalpy

ΔS = change in..

Entropy

ΔG = change in…

free energy

(combination of entropy & Enthalpy)

All combustions are endothermic/exothermic

exothermic

(ΔH<0)

ΔG=+ process is…

non spontaneous

ΔG= - process is

Spontaneous