Chemical Kinetics

Question 1

Gibbs free energy

Answer 1

determines whether or not a reaction will occur by itself without outside assistance

Question 2

High substrate conditions saturate the active sites of the enzyme,leading to

Answer 2

maximal turnover

Question 3

Reaction intermediates

Answer 3

• does not appear in the overall reaction

- difficult to detect

Question 4

Rate - determining step

Answer 4

• slowest step in the reaction

- limits the minimum rate at which the reaction can proceed

Question 5

The rate of the whole reaction is only as fast as the

Answer 5

rate determining step

Question 6

Collision theory of chemical kinetics

Answer 6

• states that the rate of a reaction is proportional to the number of collisions per second between the reacting molecules
• in order for a reaction to occur, molecules must collide with one another (not all collide, must be in correct orientation and have sufficient kinetic energy to exceed the activation energy)

Question 7

Activation energy (Ea)
(energy barrier)

Answer 7

• the minimal energy of collision for a reaction to take place

Question 8

rate of reaction equation

Answer 8

rate = Z x f

Z= total # of collisions occurring per second
f = fraction of collision that are effective

Question 9

Arrhenius equation

Answer 9

a mathematical way to represent collision theory

as the frequency factor of the reaction increases, the rate constant of the reaction also increases in a direct relationship

Therefore, rate of a reaction increases with temperature

Question 10

Transition state theory

Answer 10

• states that molecules form a transition state or activated complex during a reaction
• has greater energy than products and reactants
• the point of maximum energy

Question 11

(+) delta G = (endergonic/exergonic) = (energy absorbed/energy given off)

Answer 11

endergonic

energy absorbed

Question 12

(-) delta G = (endergonic/exergonic) = (energy absorbed/energy given off)

Answer 12

exergonic

energy given off

Question 13

Free energy change of the reaction

delta Grxn

Answer 13

the difference between the free energy change and free energy of the reactants

Question 14

Reaction rates can be affected by:

Answer 14

1. increase the conc. of reactant = increase rxn rate (all but zero-order rxns)
2. increase the temperature = increase rxn rate
3. changing the medium = can increase or decrease rxn rate
4. adding a catalyst = increase rxn rate; lowering activation energy

Question 15

Homogenous catalysts

Answer 15

same phase (solid, liquid or gas) of reactants

Question 16

Heterogenous catalysts

Answer 16

different phase (solid, liquid or gas) of reactants