2.8.2 Activation Energy

Question 1

activation energy (Ea)

Answer 1

• of a reaction is the energy required to start the reaction
• must be supplied for the reaction to begin. The energy of activation is represented by the first increase in free energy. Once the energy of activation is supplied, the reaction proceeds on its own. The difference between the energy of the products and reactants is the net free energy gain.

Question 2

enzymes

Answer 2

• work by lowering the energy of activation

Question 3

enzyme-catalyzed reaction

Answer 3

• the energy of activation is lowered. The same net energy is released, but less energy is needed to
  activate the reaction. A reaction is much more likely to proceed once the energy of activation has been lowered. If the logís activation energy was lowered, you might only have to rub it on the ground to release the energy

Question 4

Which of the following statements regarding the potential energy stored within a log is true?

Answer 4

• Potential energy is stored in the chemical bonds of the firewood

Question 5

The energy required to initiate a reaction is the

Answer 5

• activation energy

Question 6

The major effect of an enzyme in an endergonic reaction is to

Answer 6

• lower the activation energy required

Question 7

Enzymes catalyze a reaction by

Answer 7

• decreasing the amount of activation energy needed to drive the reaction

Question 8

To drive a reaction with a high positive net free energy, __________ is necessary. To speed up a reaction with a high activation energy, __________ is useful

Answer 8

• coupling with an exergonic reaction; a catalyst