Chapter 18 - Reaction Rates and Equilibrium

Question 0

How can you express the rate of a chemical reaction?

Answer 0

Change in the amount of reactants of product per unit of time.

Question 1

What is a rate?

Answer 1

It’s a measure of how much something changes within a specified amount of time.

Question 2

Define activation energy.

Answer 2

The minimum energy that colliding particles must have in order to react.

Question 3

List the four factors that can influence the rate of a chemical reaction.

Answer 3

• Temperature
• Concentration
• Particle size/agitation
• Catalysts

Question 4

What is chemical equilibrium?

Answer 4

It is when the rate of the forward reaction and the reverse reaction are equal. Review establishing equilibrium pg. 610

Question 5

What happens to the amounts of reactants and products after a reaction has reached chemical equilibrium.

Answer 5

Since chemical equilibrium is a dynamic state, both the forward and reverse reactions continue, but because their rates are equal, no net change occurs in the concentration of reaction components.

Question 6

What is equilibrium position?

Answer 6

The concentration of reactants and products at equilibrium.

Question 7

What is Le Chatelier’s principle?

Answer 7

If stress is applied to a system in dynamic equilibrium, the system changes in a way that relieves the stress.

Question 8

List three stresses that can upset the equilibrium of a chemical reactions.

Answer 8

• Change in concentration
• Change in temperature
• Change in pressure

Question 9

Define free energy

Answer 9

The energy that is available to do work.

Question 10

List the 2 characteristics spontaneous reactions share.

Answer 10

• Producing large amounts of product

- Releasing free energy

Question 11

What does the law of disorder state?

Answer 11

The natural tendency is for systems is to move in the direction of increasing disorder (entropy).

Question 12

How can you use entropy to determine whether a chemical reaction is more or less likely to be spontaneous?

Answer 12

Reactions in which entropy increases as reactants form products are more likely to be favored. (Spontaneous).

Question 13

What 2 factors determine the spontaneity of a chemical reaction?

Answer 13

• Size and direction of enthalpy changes

- Entropy changes

Question 14

When the Gibbs free energy change for a process is (-), what does this tell you about the process?

Answer 14

It’s spontaneous.

Question 15

If enthalpy increases and entropy increases as well, is the reaction spontaneous?

Answer 15

Only if the unfavorable change in enthalpy is offset by the favorable change is entropy.

Question 16

If the enthalpy decrease and the entropy decreases as well, is the reaction spontaneous?

Answer 16

Only if the unfavorable entropy change is offset by the favorable enthalpy change.

Question 17

Which way will the equilibrium position shift if the pressure is increased?

Answer 17

It will want to decrease the pressure and in order to do that it must increase the volume - that is shift to the side with less molecules.

Question 18

Which way will the equilibrium position shift if the pressure was decreased?

Answer 18

It will want to increase the pressure and in order to do that it must decrease the volume - that is shift to the side with more molecules.

Question 19

Which way will the equilibrium shift if there was an increase in the concentration of a product?

Answer 19

It will shift to the reactants’ side.

Question 20

Which way will the equilibrium shift if there was a decrease in a product’s concentration?

Answer 20

It will shift to the products’ side.

Question 21

Which way will the equilibrium position shift if you were to add heat?

Answer 21

Heat can be considered to be a product/reactant depending on the chemical equation. If heat is added, the equilibrium will shift to the reactants’ side.

Question 22

Which way will the equilibrium position shift to if heat is removed? (Considering it’s a product)

Answer 22

It will shift to the products’ side if heat is considered to be a product.

Question 23

What is a catalyst?

Answer 23

It’s a substance that increases the rate of a reaction without being used up during the reaction. They allow reactions to proceed along a lower energy path.

Question 24

What is Gibbs Free Energy?