Chapter 6 Flashcards
What is a substitution reaction?
Where one atom or group of atoms is replaced by another atom or group of atoms. One sigma bond breaks and another forms at the same carbon.
What is an elimination reaction
Where a pi bond is formed after the leaving group is removed. 1 pi bond formed, 2 sigma broken
What is an addition reaction
Where a pi bond is broken and two sigma bonds are formed
What is Homolysis
When each atom in a C-Z bond gets one electron after the bond is broken. Creates a “Radical”
What is Heterolysis
Where one atom in a C-Z bond gets both electrons after the bond is broken. Creates Carbocations/Carboanions
When deltaH is positive, is the reaction exo or endothermic? when its negative?
positive = energy is absorbed and is endothermic negative = energy is released and is exothermic
bond breaking always requires energy= positive H
bond making always releases energy = negative H
When Keq > 1 does the reaction favor the products or the reactants? Why?
Products. When Keq is greater than 1, the energy of the products is lower than the energy of of the reactants. Equilibrium favors the lower energy.
What is entropy? How does it affect equilibrium?
Measure of randomness. If the products have more compounds or elements than the starting material, entropy increases. Reactions where entropy increases are favored.
When deltaH of the reaction is (+) are the products or reactants favored? when its (-)?
(+) = starting materials (-) = reactants
How does energy of activation affect the reaction rate?
as Ea increases, Rxn rate decreases
When looking at a energy diagram, how do you determine if deltaH (-) or (+).
if end of the line is higher than the beginning, dH is (+) and starting materials are favored
if it is lower, dH is (-) and products are favored.
What is a transition state?
where the bonds between the atoms involved in the reactions are partially formed/broken. An apex of a curve on a energy diagram
How do you determine the rate determining step looking at an energy diagram.
The highest energy transition state is the rate determining step.
Which factors influence reaction rate?
Ea, Concentration, Temperature
Which factors have no effect on reaction rate?
deltaH, Keq
