Ch. 4
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Where is the electron in a free radical?
The p orbital
Initiation
Make radicals from nonradicals
Propagation
Radical reacts with nonradical
Termination
Two radicals react to form nonradicals
Keq (products and reactants)
[products]. [C]c[D]d = —————– = ———— [reactants]. [A]a[B]b
What is ∆G
the amount of energy available to do work; energy of products - energy of reactants
∆G formula
∆Gº = -RT(lnKeq); ∆Gº = ∆Hº - T∆Sº
Enthalpy
Change in bonding energy
Entropy
Change in disorder
Do cyclic molecules or acyclic molecules have more entropy?
Acyclic because cyclic molecules have restricted bond rotation
What does ∆E equal to
∆Gº
Bond dissociation ________ energy, bond formation ________ energy
requires, releases
Homolytic cleavage
When the bond breaks, each atom gets one electron
Heterolytic cleavage
When the bond breaks, the most electronegative gets both electrons
What range do most BDE fall between
60-100 kcal/mol
Rate law equation (for A+B –> C + D)
rate = kr[A]a[B]b
What is order
Order is the number of molecules of that reactant which is present in the rate-determining step of the mechanism
Rate constant formula
kr = Ae^(-Ea/RT)
What is activation energy
the minimum kinetic energy needed to react
What is the value of R (gas constant)
8.314 J/Kmol
Intermediates
Short-lived species on the way to a product
Transition states
the highest point in energy between two chemicals
Rate Determining Step
The slowest step in the reaction will have the highest energy transition state
With ____ Ea, rate decreases
increasing