AP Chem Unit 6 Thermodynamics

Exothermic

A reaction in which energy is released into the surroundings as heat.

Endothermic

A reaction in which energy is absorbed from the surroundings.

System

The portion of the experiment focused on, consisting of the reactants and products.

Surroundings

Everything outside the system, including the container and everything else.

ΔH < 0

Indicates an exothermic process.

ΔH > 0

Indicates an endothermic process.

Calorimetry

The process used to determine how much heat is absorbed or released.

Specific heat capacity

The amount of heat required to raise the temperature of 1 gram of a substance by 1 °C.

ΔE = q + w

The equation representing the change in internal energy of the system as the sum of heat (q) and work (w).

Thermal equilibrium

The condition when two substances at different temperatures reach the same temperature.

First law of thermodynamics

States that energy cannot be created or destroyed, only transformed.

Heat (q)

The transfer of energy that occurs due to a temperature difference.

Temperature change (ΔT)

The difference in temperature experienced by a substance.

Heat capacity

The measure of the heat required to change a substance's temperature.

Bond enthalpy

The energy required to break a bond or the energy released when a bond is formed.

Hess's Law

States that the total enthalpy change for a reaction is the sum of the enthalpy changes for individual reactions.

Energy diagrams

Visual representations showing the changes in potential energy throughout a reaction.

Instant hot pack

An example of an exothermic process where heat is released when activated.

Instant cold pack

An example of an endothermic process where heat is absorbed when activated.

Phase changes

Transitions between solid, liquid, and gas states, often involving energy changes.

Heat of fusion

The energy required to change a substance from solid to liquid at its melting point.

Heat of vaporization

The energy required to change a substance from liquid to gas at its boiling point.