Physical Chemistry: Branches and Principles

Physical Chemistry

Branches of Physical Chemistry

• Thermochemistry: study of heat changes in chemical reactions
• Chemical Kinetics: study of rates of chemical reactions
• Electrochemistry: study of chemical reactions involving electron transfer
• Quantum Mechanics: study of behavior of atoms and molecules at atomic and subatomic level
• Spectroscopy: study of interaction between matter and electromagnetic radiation

Laws and Principles

• Zeroth Law of Thermodynamics: if two systems are in thermal equilibrium with a third system, they are also in thermal equilibrium with each other
• First Law of Thermodynamics: energy cannot be created or destroyed, only converted from one form to another
• Second Law of Thermodynamics: total entropy of an isolated system always increases over time
• Third Law of Thermodynamics: as temperature approaches absolute zero, entropy approaches a minimum value

Important Concepts

• Thermodynamic Systems: isolated, closed, and open systems
• State Functions: properties that depend only on the current state of the system, not on the path by which it was reached (e.g. internal energy, entropy)
• Phase Equilibria: equilibrium between different phases of a substance (e.g. solid-liquid, liquid-gas)
• Chemical Potential: measure of the energy associated with a substance's chemical reactions

Physical Chemistry

Branches of Physical Chemistry

• Thermochemistry is the study of heat changes in chemical reactions.
• Chemical Kinetics is the study of rates of chemical reactions.
• Electrochemistry is the study of chemical reactions involving electron transfer.
• Quantum Mechanics is the study of behavior of atoms and molecules at atomic and subatomic level.
• Spectroscopy is the study of interaction between matter and electromagnetic radiation.

Laws and Principles

• The Zeroth Law of Thermodynamics states that if two systems are in thermal equilibrium with a third system, they are also in thermal equilibrium with each other.
• The First Law of Thermodynamics states that energy cannot be created or destroyed, only converted from one form to another.
• The Second Law of Thermodynamics states that the total entropy of an isolated system always increases over time.
• The Third Law of Thermodynamics states that as temperature approaches absolute zero, entropy approaches a minimum value.

Important Concepts

Thermodynamic Systems

• Isolated systems exchange neither matter nor energy with the surroundings.
• Closed systems exchange energy but not matter with the surroundings.
• Open systems exchange both matter and energy with the surroundings.

State Functions

• State functions are properties that depend only on the current state of the system, not on the path by which it was reached.
• Examples of state functions include internal energy and entropy.

Phase Equilibria

• Phase equilibria occurs when a substance is in equilibrium between different phases (e.g. solid-liquid, liquid-gas).
• The equilibrium is characterized by equal chemical potential of the substance in each phase.

Chemical Potential

• Chemical potential is a measure of the energy associated with a substance's chemical reactions.
• It is a driving force behind chemical reactions and phase transitions.