Free Energy and Thermodynamics

Spontaneous Process

Process occurs without any ongoing outside influence

Non-spontaneous process

Occurs only with a continuous outside influence

Formal Definition of Entropy

Is a thermodynamic function that increases with the number of energetically equivalent ways to arrange the components of a system in a particular state

Formal Definition of Entropy

Entropy is a measure of the energy randomization, or energy dispersal, within a system

State of a System

A state is a description of a system at a given time

Microstates

Describes the exact arrangement of the components within a system

The second Law of Thermodynamics

A spontaneous process increases the entropy of the universe

Phase Transition

Both states of matter are present during a phase change

Melting

Phase change from a solid to a liquid

Freezing

Phase change from a liquid to a solid

Vaporization

Phase change from a liquid to a gas

Condensation

Phase change from a gas to a liquid

Sublimation

Transition from solid to gas

Deposition

Transition from gas to solid

System

Thing that is under investigation

Surroundings

Everything else with which the system can exchange energy

Entropy changes for system and surroundings

• the second law of thermodynamics tells us that a spontaneous process increases the entropy of the universe

• The entropy of the system can decrease as long as it is accompanied by a greater increase in the entropy of the surrounding

What is the equation for Entropy Changes in Surroundings

What is the Gibbs Free Energy equation?

Negative Delta G

Process is spontaneous

Positive Delta G

Process is not spontaneous

Gibbs Free Energy as Chemical Potential

Is useful because it is analogous to mechanical potential

• systems tend toward lower free energy

Standard states

Are reference conditions for a given material

• a degree sign is used to designate standard state conditions

What are the standard state conditions for a gas?

• pure gas with a pressure of 1 bar

• The pressure of a gas in its standard state used to be 1 atm, both standard are now in common use

What are the standard state conditions for a solids, and liquid?

Pure substance in its most stable form at a pressure of 1 atm and at the temperature of interest (usually 25 degrees)

What is the Standard Enthalpy Change for a Reaction ( Delta H rxn) equation?

Standard Molar Entropies

A measure of the energy dispersed into one mole of a substance at a particular temperature

Third Law of Thermodynamics

the entropy of a perfect crystal at absolute zero (0 K) is zero

What is the equation for Standard Entropy Changes for a Reaction (Delta S rxn) ?

What is the Calculations for Standard Free Energy Changes Using Equation for Gibbs Free Energy?

Standard Free Energy changes using Equation for Gibbs Free Energy

Standard enthalpies of formation standard molar entropies can be used to calculate the standard free energy changes using of a reaction