Chemistry Chapter 13 - Thermochemistry

Thermochemistry

the branch of science that studies the transfer of energy during chemical reactions or phase changes

enthalpy

thermal energy content of a system at a constant pressure

calorimeter

an insulated container in which a thermometer detects the temperature change that occurs during a reaction

sensible heat

heat that produces a temperature change in a substance when applied

latent heat

heat that produces a phase change in a substance

molar enthalpy of fusion

the quantity of energy required to melt one mole of a solid to a liquid with no temperature change

molar enthalpy of vaporization

the quantity of energy required to convert a mole of a liquid at its boiling point to its vapor at the same temperature

specific heat

the amount of thermal energy required to raise the temperature of 1 g of the substance by 1 degree celsius

enthalpy of reaction

the change in enthalpy that occurs during a reaction

thermochemical equation

a chemical equation that shows the reactants, products, and amount of energy released or absorbed

standard molar enthalpy of combustion

the energy released as heat by the complete burning of one mole of a substance at standard conditions

Hess’s law

states that the enthalpy change of a reaction equals the sum of the enthalpy changes for each step of the process

Entropy

a measure of the dispersal of energy in a system

Gibbs free energy (G)

a combination of the chang ein enthalpy and the change in entropy

second law of thermodynamics

states that natural processes tend to decrease the usable energy in the universe