Spontaneity, Entropy, and Free Energy Notes

Entropy (S)

A measure of disorder or randomness in a system.

Spontaneous Reaction

A reaction that occurs without external intervention, thermodynamically favorable.

Thermodynamics

A branch of physics that deals with heat and temperature and their relation to energy and work.

First Law of Thermodynamics

The energy of the universe is constant; energy cannot be created or destroyed.

Second Law of Thermodynamics

Entropy of the universe increases; natural processes tend to move toward a state of greater disorder.

Positional Probability

The number of ways a given system can be arranged in a particular state, contributing to its entropy.

Free Energy (9G)

The amount of energy in a system that can be used to do work, can predict the spontaneity of a reaction.

Gibb's Free Energy Equation

9G = 9H - T9S, relates changes in freedom energy (9G) to changes in enthalpy (9H) and entropy (9S).

Third Law of Thermodynamics

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

Equilibrium Condition

Occurs when 9G = 0 and the reaction quotient (Q) equals the equilibrium constant (K).

Endothermic Reaction

A reaction that absorbs heat from the surroundings, resulting in positive 9H.

Exothermic Reaction

A reaction that releases heat to the surroundings, resulting in negative 9H.

Calculating 9S

The change in entropy 9S for a reaction is calculated using the formula: 9S = 9Sonproducts - 9Sonreactants.

Reaction Kinetics

The study of the rates at which chemical processes occur, influenced by factors such as temperature, concentration, and catalysts.

Activation Energy

The minimum energy required for a chemical reaction to occur.

Rate Law Expression

An equation that relates the rate of a chemical reaction to the concentration of its reactants.

Catalyst

A substance that speeds up a chemical reaction without being consumed in the process; does not affect 9G.

Standard Enthalpy Change (9H)

Enthalpy change when one mole of a compound is formed from its elements at standard conditions.