Thermodynamics vs. kinetics in chemical reactions

Thermodynamics vs. kinetics in chemical reactions
Thermodynamics dictates equilibrium (which says whether
this reaction will take place).
Says nothing about what rate (how fast) the reaction will
be.
In a spontaneous reaction, ΔG is negative. When ΔG is
negative, reaction is spontaneous.
ΔG (Gibbs free energy) follows this fomula : ΔG=ΔH - TΔS.
It is largely dependent on two concepts :
Enthalpy : ΔH. Negative values of this (i.e. exothermic)
decrease ΔG, making the reaction more favorable.
Entropy : - TΔS. The T represents temperature. The S
represents entropy, or a measurement of disorder. This
term in the equation is negative and temperature is
always positive. Therefore, increasing the change in
entropy (positive ΔS) makes the reaction more favorable.
The endothermic or exothermic qualities of a reaction are
indicated by ΔH (enthalpy).
Negative enthalpy indicates exothermic reaction
Positive enthalpy indicates endothermic reaction
Note that because ΔG is dependent on both enthalpy and
entropy, it is possible for endothermic reactions to proceed
spontaneously.
Thermodynamics is independent of reaction mechanism
(concerned with original and final states only).
Thermodynamics concerns the equilibrium constant K
(upper-case).
Kinetics involves the rate of the reaction
Kinetics is affected by catalysts. The rate of the reaction
involves the activation energy. Catalysts lower the
activation energy, which causes the reaction to speed up.
Kinetics concerns the rate constant k (lower-case).
Examples of thermodynamics-kinetics feuds :
Combustion (aka burning) of my physical chemistry book
is thermodynamically favored. Unfortunately, it is not
favored kinetically because the activation energy for the
combustion reaction is too high for the present conditions.
One could always invest a little energy in the form of a
flame and start the reaction. The energy produced from the
combustion would supply the activation energy of the next
reaction.
The conversion of diamond into graphite is
thermodynamically favored (negative ΔG.) The speed of
this reaction is just too darn incredibly slow for a diamond
to turn into graphite.
Thermodynamics
Kinetics
Determines
Equilibrium (product vs. reactant)
Speed of reaction
Constant
K (uppercase) = equilibrium constant
k (lowercase) = rate constant
Determined by
ΔG (enthalpy and entropy)
activation energy
Buzzwords
Entropy, enthalpy, Gibbs free energy, spontaneous, endo-
and exothermic, equilibrium
Rate, speed, time, catalyst, enzyme, activation energy,
reaction order, first-order, second-order, rate-limiting step,
bottleneck