Thermochemistry and Phase Changes Flashcards

Flashcards covering thermochemistry, phase changes, and related calculations.

Thermochemistry

Study of energy transfers as heat during chemical reactions and physical changes

Heat

Energy transfer between matter due to temperature differences

Enthalpy (H)

Sum of a system's internal energy plus the product of pressure and volume

Entropy

Measure of disorder or randomness in a system

Bond Energy

Energy required to break a chemical bond between atoms (measured in Kj/mole)

Heat of Fusion

Energy needed to change a substance between solid and liquid states

Heat of Vaporization

Energy needed to change a substance between liquid and gas states

Latent Heat

Energy used to loosen molecular bonds during phase changes

Critical Point

Temperature and pressure where distinction between liquid and gas phases disappears

Triple Point

Conditions where all three states of matter coexist

Specific Heat Capacity (c)

Amount of heat needed to raise 1g of substance by 1°C

Joule (J)

Unit of energy defined by work done by 1 newton force over 1 meter

ΔH

Change in enthalpy (negative for exothermic, positive for endothermic reactions)

Hess's Law

States that total enthalpy change equals sum of individual step changes