activation energy
the difference between the energy of an activated complex and the energy of the reactants of a chemical reaction; the energy with which particles must collide in order to react
activated complex
a collection of intermediate structures in a chemical reaction that persist while bonds break and new bonds form; a range of configurations that atoms pass through in between clearly defined products and reactants.
catalysis
the alteration of the rate of a chemical reaction because of the presence of a catalyst
catalyst
a substance that increases the rate of a chemical reaction by lowering the activation energy without being chemically changed by the reaction
endothermic reaction
a chemical process that absorbs heat
enthalpy
the heat content of a system at constant pressure
entropy
a quantitative measure of the disorder or randomness of a system
equilibrium
the concentrations of the reactants and products are constant and their ratio does not vary; forward and reverse reactions occur at the same rate
exothermic reaction
a chemical process that releases heat
forward reaction
a chemical reaction that proceeds from left to right
Le Chatelier's Principle
a principle that states that a reversible reaction at equilibrium will shift is a direction that will offset a stress such as pressure or concentration changes, imposed on a system
potential energy
the energy possessed by a body by virtue of its position relative to others, stresses within itself, electric charge, and other factors.
potential energy diagram
a diagram that shows the potential energy changes of the substances in a reaction over a period of time
reaction rates
changes in the concentration of reactants and products per unit of time as the reaction proceeds
reaction rates
changes in the concentration of reactants and products per unit of time as the reaction proceeds
reversible reaction
a reaction in which the conversion of reactants to products and the conversion of products to reactants occurs simultaneously
spontaneous reaction
a process that proceeds on its own without any outside intervention