Chem 123/125 Midterm 2

What is the activation energy for this reaction?

• 42 536.2 J

• 88 988.1 J mol-1

• 42 536.2 J mol-1

• 88 988.1 J

By what factor does k increase if the temperature increases from 5℃ to 20℃.

• 4.21

• 3.06

• 2.56

• 2.97

What is the relationship between activation energy and rate constant (k)?

• As activation energy decreases, k decreases.

• As activation energy increases, k decreases.

• As activation energy decreases, k increases.

• As activation energy increases, k increases.

The rate law is always expressed in terms of concentration of reactants, products, and/or catalysts.

• True

• False

Which of the following statements regarding catalysts in chemical reactions are true?

• Catalysts lower the activation energy

• They are consumed in one step

• Regenerated in subsequent step

• All of the above

Which statement is true when the forward rate of reaction is equal to the reverse rate of reaction?

• The reaction does not stop at the molecular level.

•  The system is approaching equilibrium.

•  The concentration of the reactants decreases.

• The concentration of the products decreases.

If you double the concentration of S8, by what factor does Q change?

• Decreases by a factor of 4

• Decreases by a factor of 16

• Increases by a factor of 4

• Increases by a factor of 16

What is the direction of the reaction when the initial pressure of both gasses is 1.2 bar and the Kc is 5.3?

• Reverse

•  Forward

•  It is at equilibrium

•  Not enough information

If the equilibrium constant is 700000, the reaction will not go very far towards products.

• True

• False