organic chemistry exam #2 chapter 6
Which value of ΔG corresponds with Keq = 1? 0 kJ/mol -1 kJ/mol +1 kJ/mol
0 kj/mol
when will delta s be positive?
1. more moles of product formed than moles of reactant 2. when a cyclic compound becomes acyclic
What is a transition state? An isolable intermediate in a reaction. The starting materials of the reaction. A local maximum on the energy diagram. A low-energy point between the starting materials and the product
A local maximum on the energy diagram. transitions states are maximum PE on graph
What is an intermediate? A local maximum on the energy diagram. A point on the reaction pathway that has a discrete minima. A point half-way between the starting materials and products. The highest energy compound on an energy diagram.
A point on the reaction pathway that has a discrete minima.
enthalpy
H total kinetic and PE of a system at constant pressure
Which of the following describes the effect of a catalyst on a reaction? It lowers the free energy of the products. It makes the reactants less stable. It changes the equilibrium constant. It lowers the energy of activation.
It lowers the energy of activation.
catalyst lowers...
activation energy
what is it called in order to BREAK a covalent bond?
bond dissociation energy (delta H)
what contributes to frequency of collisions
concentration of reactants activation energy temperature congestion catalyst
hyperconjugation
delocalization of electrons by the overlap of a sigma orbital with an empty orbital
change in enthalpy
delta H exchange of heat between system and its surroundings also called bond dissociation energy
entropy
disorder if positive: spon
positive delta g is exergonic or endergonic?
endergonic
Which of the following indicates a reaction with a positive ∆G? endergonic, spontaneous endergonic, not spontaneous exergonic, spontaneous exergonic, not spontaneous
endergonic, not spontaneous
negative delta g is exergonic or endergonic?
exergonic
exothermic vs. endothermic reaction and delta h
exo = - delta h endo = + delta h
the lower the activation energy -->
faster the rate
a more positive Keq -->? a smaller Keq-->?
favors products favors reactants
Given the following rate law, what is the order of the reaction with respect to MeI? rate =k[Mel][NaCN] zero first second third None of the above
first
homolytic vs heterolytic
homolytic: each atom gets an electron (radicals) heterlytic: 2 ions (one gets both electrons)
a fast reaction means?
large rate constant
bond forming
negative exothermic
negative delta g vs. positive delta g which is spon?
negative delta g = spon positive delta g = nonspon
nucleophiles vs. electrophiles
nucleophiles: electron rich electrophiles: electron poor
nucleophilic centers are...
pi bonds, lone pairs
bond breaking
positive endothermic
Does a reaction with a Keq = 10 favor reactants or products? reactants products cannot determine without additional information
products
Does a reaction with a positive ΔG favor reactants or products? reactants products cannot determine without additional information
reactants
in an exothermic reaction - transition state resembles... in an endothermic reaction - transition state resembles...
reactants products
Given the following rate law, what is the order of the reaction with respect to sodium cyanide? rate =k[Mel][NaCN]^2 zero first second third None of the above
second
Of the following factors, which will affect the rate of reaction? ΔG Temperature ΔH Ea Keq ΔS
temp and ea -Keq only affects equilibrium, not rate -G affects equilibrium, not rate -S and H both affect G, which affect equilibrium, not rate
An exothermic reaction for which the system exhibits an increase in entropy. ΔG will decrease with raising the temperature. ΔG will be positive. ΔG will increase with raising the temperature. ΔG will be negative.
ΔG will be negative.
An endothermic reaction for which the system exhibits a decrease in entropy. ΔG will decrease with raising the temperature. ΔG will be positive. ΔG will be negative. ΔG will increase with raising the temperature.
ΔG will be positive.
An endothermic reaction for which the system exhibits an increase in entropy. ΔG will increase with raising the temperature. ΔG will decrease with raising the temperature. ΔG will be positive. ΔG will be negative.
ΔG will decrease with raising the temperature.
An exothermic reaction for which the system exhibits a decrease in entropy. ΔG will increase with raising the temperature. ΔG will be negative. ΔG will be positive. ΔG will decrease with raising the temperature.
ΔG will increase with raising the temperature.
