Chapter 15: Energy and Chemical Change

thermochemical equation

A balanced chemical equation that includes the physical states of all reactants and products and specifies the change in enthalpy.

Heat (q)

A form of energy that flows from a warmer object to a cooler object.

potential energy

Energy stored in an object due to its composition or position.

Surroundings

Includes everything in the universe except the system. (Air)

Endothermic

Reactions in which the system absorbs energy from the surroundings.

Exothermic

Reactions in which the system releases energy to the surroundings.

Law of Conservation of Energy

States that in any chemical or physical process, energy may change from one form to another but is neither created nor destroyed.

Joule (J)

The SI unit of heat and energy.

Specific heat (c)

The amount of heat required to raise the temperature of one gram of a given substance by one degree Celsius.

Calorie (cal)

The amount of heat required to raise the temperature of one gram of pure water by one degree Celsius.

enthalpy (heat) of reaction

The change in enthalpy for a reaction; ( The difference between the enthalpy of the products and the enthalpy of the reactants. )

kinetic energy

The energy of motion.

chemical potential energy

The energy stored in a substance because of its composition (what it is)

Enthalpy (H)

The heat content of a system at constant pressure.

System (thermochemistry)

The specific part of the universe containing the reaction or process being studied. (Where it occurs, a beaker)

Thermochemistry

Then study of heat changes that accompany chemical reactions and phase changes.

Universe

is the system plus the surroundings

Energy

the capacity to do work or produce heat