14-3

Question 1

Activation energy on a graph equals

Answer 1

-Slope * R (R is a constant = 8.314)

Question 2

For the reaction to proceed, the energy barrier (activation energy)

Answer 2

must be “crossed”. At the highest energy state, the transition state (activated complex) is formed.​

Question 3

Activation energy is the energy needed to form (reach)

Answer 3

the transition state.​
Transition state is not a stable species. It lasts shorter time than one vibration. ​

Question 4

Another factor to consider, which affects the rate​ is the…

Answer 4

Orientation of molecules (14.3-pg.8)

Question 5

There is a big difference between the transition state and the intermediate. What is it?

Answer 5

transition states are not stable species. ​
Intermediates are stable. In some instances, it is possible to isolate an intermediate.​

Question 6

Catalysts increase the rate of a reaction…

Answer 6

without being used up themselves, by decreasing the activation energy of the reaction.​

Catalysts do this by changing the mechanism by which the process occurs (more elementary steps, but with smaller activation energies).​

Catalyst reacts in one step and is regenerated in another step, so it does not appear in the net equation.​

Question 7

Type of catalysts are…

Answer 7

Homogeneous catalysts​
Heterogeneous catalysts​
Enzymes – Nature’s Catalysts​

Question 8

Homogeneous Catalysts​ are

Answer 8

The reactants and catalyst are in the same phase.​

Question 9

Heterogeneous Catalysts​ are

Answer 9

The catalyst is in a different phase than the reactants.​
Often, gases are passed over a solid catalyst.
The adsorption of the gas molecules of the reactants on the surface of a solid catalyst is often the rate-determining step.​​

Question 10

Enzymes​ are

Answer 10

biological catalysts
Enzymes are very specific. ​
The substrate fits into the active site of an enzyme, much like a key fits into a lock.​