Chemistry Lecture Review

Flashcards for key vocabulary and concepts.

Phase Change

A physical process in which a substance goes from one phase to another; occurs when adding or removing heat at a particular temperature.

Temperature

A measure of the average kinetic energy of particles of a substance.

Melting Point

The temperature at which a substance goes from a solid to a liquid (or from a liquid to a solid).

Boiling Point

The temperature at which a substance goes from a liquid to a gas (or from a gas to a liquid).

Endothermic

A reaction in which heat is absorbed; heat flows into the system.

Exothermic

A reaction in which heat is released; heat flows out of the system.

System

The set of substances and energy that is being studied.

Surroundings

Everything that is not part of the system.

Specific Heat Capacity

The quantity of heat required to raise the temperature of one gram of a substance by one °C.

Enthalpy

Heat

Enthalpy of Formation (ΔHfus)

The amount of heat needed for solid molecules to become liquid molecules (or for liquid molecules to become solid).

Enthalpy of Vaporization (ΔHvap)

The amount of heat required for liquid molecules to become gaseous molecules (or for gas molecules to become liquid).

Enthalpy of Reaction (ΔHRxn)

The difference in enthalpy of the reactants and products.

Le Chatelier's Principle

If a chemical reaction at equilibrium is disturbed by changing the reaction conditions, the position of equilibrium shifts to counteract the change and re-establish equilibrium.

Activation Energy (Ea)

The barrier that must be overcome for reactants to be able to become products.