AP Chem Thermo Vocab

Energy (E)

The ability to do work or produce heat. The sum of all the potential and kinetic energy in a system is known as the internal energy of the system. Measured in joules

potential energy

stored energy. In chemistry, this is usually referring to the energy stored in molecular bonds

kinetic energy

the energy of motion. Usually, the energy of particles in a sample is proportional to the Kelvin temperature. Depends on the mass and the square of the velocity of the particle

Law of conservation of energy

Energy is never created nor destroyed. The energy of the Universe is constant. First law of thermodynamics

heat (q)

the transfer of energy due to a temperature difference in a physical or chemical process. Always flows from a warmer object to a cooler one. Transfers because of a temperature difference. Measured in joules

specific heat capacity (Cp)

the energy required to raise the temperature of one gram of a substance by one degree Celsius

molar heat capacity

the energy required to raise the temperature of one mole of a substance by one degree Celsius

calorie

the amount of heat needed to raise the temperature of one gram of water by one degree Celsius. 4.184 J

kilocalorie

food calorie, represented by a capital C

enthalpy (H)

A measure of heat content at constant pressure

enthalpy of reaction (ΔHrxn)

heat absorbed or released by a chemical reaction

enthalpy of combustion (ΔHcomb)

heat released when one mole of a substance is burned in the presence of oxygen

enthalpy of formation (ΔHf)

heat absorbed or released when one mole of a compound is formed from elements in their standard states

enthalpy of fusion (ΔHfus)

heat absorbed to melt one mole of solid to liquid at the normal melting point

enthalpy of vaporization (ΔHvap)

heat absorbed to change one mole of liquid to gas at the normal boiling point

enthalpy of neutralization (ΔHneut)

heat absorbed or released when a neutralization reaction occurs

endothermic

the net absorption of energy (heat) by the system. Energy is a reactant; ΔH is positive.

exothermic

the net release of energy (heat) by the system. Energy is a product; ΔH is negative

state function

A property that is independent of past or future behavior, written in all capital letters

entropy (S)

A measure of disorder in the system, or a measure of chaos (second law of thermodynamics). The universe tends toward a state of greater disorder in spontaneous reactions

Gibbs free energy (G)

the amount of free energy to do work

thermodynamics

the study of energy and its interconversions in physical and chemical processes