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188 Chapter 5
Copyright © 2017 Pearson Education, Inc.
exothermic reaction
a reaction with a negative
∆
H
°
.
experimental energy of
a measure of the approximate energy barrier to a reaction.
activation
(It is approximate because it does not contain an entropy component.)
1
E
a
∆
H
[
RT
2
free energy of activation
the energy barrier to a reaction.
1
G
[
2
functional group
the center of reactivity of a molecule.
Gibbs free-
the difference between the free energy of the products and the free energy
energy change
1
G
2
of the reactants at equilibrium under standard conditions (1M, 25
°
C, 1 atm).
heat of hydrogenation
the heat (
∆
H
°
) released in a hydrogenation reaction.
hydrogenation
addition of hydrogen.
intermediate
a species formed during a reaction that is not the final product of the reaction.
kinetics
the field of chemistry that deals with the rates of chemical reactions.
kinetic stability
indicated by
∆
G
[
. If
∆
G
[
is large, the compound is kinetically stable (is not very
reactive). If
∆
G
[
is small, the compound is kinetically unstable (is very reactive).
Le Châtelier’s principle
a principle that states that if an equilibrium is disturbed, the components of the
equilibrium will adjust to offset the disturbance.
mechanism of the reaction
a description of the step-by-step process by which reactants are changed into
products.
metabolic pathway
a series of reactions that convert complex nutrient molecules to simple molecules.
molecular recognition
the ability of one molecule to recognize another as a result of intermolecular
interactions.
nucleophile
an electron-rich atom or molecule.
pheromone
a chemical substance used for the purpose of communication.
rate constant
the proportionality constant in the rate law.
rate of a reaction
the speed at which the reactants are converted to products.
rate-determining step
the step in a reaction that has the transition state with the highest energy.
or
rate-limiting step