Physical Chemistry Lecture Flashcards

Flashcards covering key concepts and definitions from the Physical Chemistry lecture.

First Law of Thermodynamics

Energy cannot be created or destroyed, only transformed.

Internal Energy (U)

The total energy contained within a system based on its temperature and pressure.

Enthalpy (H)

A thermodynamic quantity representing the total heat content of a system, equal to internal energy plus pressure times volume (H = U + pV).

Open System

A system that can exchange both energy and matter with its surroundings.

Closed System

A system that can exchange energy but not matter with its surroundings.

Isolated System

A system that can exchange neither matter nor energy with its surroundings.

Exothermic Process

A process that releases heat to its surroundings.

Endothermic Process

A process that absorbs heat from its surroundings.

Diathermic Wall

A wall that permits heating as a mode of transfer of energy.

Adiabatic Wall

A wall that does not permit heating, resulting in no heat transfer.

Heat Capacity (C)

The amount of energy required to change the temperature of a system by one degree.

Work (W)

The energy transferred to or from a system when it is subjected to an opposing force.

Molecule

A neutral particle made of two or more atoms bonded together.

Ion

A positively or negatively charged particle.

Heat (q)

The transfer of thermal energy between systems and their surroundings.

Hess’s Law

The principle stating that the total enthalpy change in a chemical reaction is equal to the sum of the enthalpy changes in the steps.

Phase Transition

The conversion of one phase of a substance to another phase (e.g., solid to liquid).

Bond Enthalpy

The amount of energy required to break one mole of a bond in a molecule.

Standard Enthalpy of Formation (ΔfHo)

The change in enthalpy when one mole of a pure substance is formed from its elements in their standard states.