ch16-17 chem reaction thermochemistry

thermochemistry

The study of the transfers of energy as heat that accompany chemical reactions and physical changes.

temperature

A measure of the average kinetic energy of the particles in a sample of matter.

calorimeter

Instrument used to measure the energy absorbed or released as heat in a chemical reaction and physical changes.

enthalpy change

The amount of energy absorbed/released by a system as heat during a process at constant pressure.

thermochemical equation

An equation that includes the quantity of energy released or absorbed as heat during that reaction as written.

entropy

A measure of the degree of randomness/disorder of the particles, such as molecules in a system.

entropy change

A measure of the difference between entropy of the products and the reactants.

free energy

The energy available to do work.

free energy change

The difference between the enthalpy and the product of the Kelvin temperature, and the entropy change at constant temperature and pressure.

collision theory

The set of assumptions regarding collisions and reactions.

activation energy

The minimum amount of energy required to transform the reactants into the activated complex.

activated complex

A transitional structure that results from an effective collision and that persists while old bonds are breaking and new bonds are forming.

reaction rate

The change in concentration of the reactants per unit of time as the reaction proceeds.

reaction mechanism

The step-by-step sequence of reactions by which the overall chemical change occurs.

intermediate

Species that appear in some steps but not in the net equation.

catalyst

A substance that changes the rate of the chemical reaction without itself being consumed.

rate-determining step

The slowest step of the chemical reaction that determines the rate law.