Question 1

Which part of an energy diagram represents the activation energy for a chemical reaction?

Accepted Answer

The highest point on the curve minus the energy of the reactants: $$E_a = E_{TS} - E_{reactants}.$$

Question 2

In an energy diagram, what does a negative enthalpy change ($$\Delta H) $$indicate about the reaction?

Accepted Answer

The reaction is exothermic and releases energy.

Question 3

Given the following activation energies: Reaction A ($$E_a = 143 kJ$$), Reaction B ($$E_a = 80 kJ$$), Reaction C ($$E_a = 215 kJ$$), which reaction will occur the fastest?

Accepted Answer

Reaction B

Question 4

If the energy of the reactants is $$120 kJ $$and the energy of the products is $$90 kJ$$, what is the enthalpy change ($$\Delta H) $$for the reaction?

Accepted Answer

$$\Delta H = -30 kJ$$

Question 5

Which statement is true regarding a reaction with a high activation energy?

Accepted Answer

The reaction will proceed slowly unless catalyzed.

Question 6

A reaction has an activation energy of $$40 kJ $$and an enthalpy change of $$-25 kJ. $$Which of the following best describes the reaction?

Accepted Answer

Exothermic with a low activation energy.

Question 7

Which of the following energy diagrams represents the slowest reaction?

Accepted Answer

A diagram with the highest activation energy.

Question 8

What is the overall energy change ($$\Delta H) $$for a reaction where the reactants start at $$60 kJ $$and the products end at $$35 kJ$$?

Accepted Answer

$$\Delta H = -25 kJ$$

Question 9

Which of the following best describes the transition state in a reaction energy diagram?

Accepted Answer

The highest energy point along the reaction coordinate.

Question 10

A reaction releases $$30 kJ of $$energy and has an activation energy of $$70 kJ. $$What is the energy of the transition state if the reactants start at $$100 kJ$$?

Accepted Answer

$$170 kJ$$

Question 11

Which factor will increase the rate of a chemical reaction according to the energy diagram?

Accepted Answer

Decreasing the activation energy.

Question 12

If a reaction is endothermic, which of the following is true about the energy diagram?

Accepted Answer

The products have higher energy than the reactants.

Question 13

Which of the following statements is true regarding the speed of a reaction?

Accepted Answer

A higher activation energy results in a slower reaction.

Question 14

What does the reaction coordinate axis represent in an energy diagram?

Accepted Answer

The progress of the reaction from reactants to products.

Question 15

A reaction has reactants at $$80 kJ$$, a transition state at $$150 kJ$$, and products at $$60 kJ. $$What is the activation energy?

Accepted Answer

$$70 kJ$$

Question 16

Which of the following is a correct definition of activation energy ($$E_a$$)?

Accepted Answer

The minimum energy required for reactants to form products.

Question 17

If the overall energy change ($$\Delta H) $$for a reaction is positive, what does this mean?

Accepted Answer

The reaction is endothermic.

Question 18

Which of the following would make a reaction more favorable according to Gibbs Free Energy ($$\Delta G$$)?

Accepted Answer

A negative $$\Delta G.$$

Question 19

In a medical scenario, why is it important for metabolic reactions to have low activation energies?

Accepted Answer

To allow reactions to occur rapidly at body temperature.

Question 20

Which of the following best describes the effect of a catalyst on an energy diagram?

Accepted Answer

It decreases the activation energy.

Energy Diagrams and Reaction Energetics in GOB Chemistry

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