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.