Chapter 1 Review: Energy and Reaction Rate ✓

Question 1

What is energy?

Answer 1

Energy is the capacity to do work or cause change

Question 2

What is energy measured in?

Answer 2

Joules (J)

Question 3

What are some forms of energy?

Answer 3

-Heat
-Chemical
-Electrical
-Light
-Kinetic
-Potential

Question 4

What is a system?

Answer 4

The reaction mixture

Question 5

What is the surroundings?

Answer 5

The object holding the mixture and anything else around it

Question 6

What is the Law of Conservation?

Answer 6

Energy is neither created nor destroyed. Energy changes from one form of energy into another form

Question 7

What is enthalpy?

Answer 7

A measure of the energy present in a substance

Question 8

What happens during a chemical change in terms of the bonds?

Answer 8

Some bones are broken and new ones are formed which causes a change in the amount of stored chemical potential energy

Question 9

What is enthalpy change?

Answer 9

The amount of heat energy transferred during a chemical reaction at constant pressure

Question 10

How to find enthalpy change?

Answer 10

enthalpy of products - enthalpy of reactants

Question 11

What is an exothermic reaction and give an example of one.

Answer 11

Reactions that lose heat to the surroundings (e.g. combustion

Question 12

Is the value of enthalpy change negative or positive for an exothermic reaction?

Answer 12

Negative because enthalpy decreases during the course of the reaction

Question 13

Why do exothermic systems feel hot?

Answer 13

Exothermic systems feel hot because energy is released to the surroundings as bonds form. This causes a decrease in enthalpy (chemical potential energy), as some of the chemical potential energy stored in bonds is converted into particle kinetic energy. The increase in particle kinetic energy leads to a rise in the system’s temperature, making it feel hot.

Question 14

What is chemical potential energy?

Answer 14

The energy stored in the chemical bonds of a substance

Question 15

How is chemical potential energy released?

Answer 15

Through a chemical reaction

Question 16

What is kinetic energy?

Answer 16

A form of energy that an object or a particle has by reason of its motion

Question 17

What are endothermic reactions and give an example of one.

Answer 17

They are reactions that gain heat from the surroundings (e.g. ice melting)

Question 18

Is the value of enthalpy change negative or positive for an enothermic reaction?

Answer 18

Positive because enthalpy increases during the course of the reaction

Question 19

Why do endothermic systems feel cold?

Answer 19

Endothermic systems feel cold because energy is absorbed from the surroundings to break bonds. This causes an increase in enthalpy (chemical potential energy) as some of the kinetic energy of the particles is converted into potential energy stored in bonds. The decrease in particle kinetic energy leads to a lower temperature in the reacting system, making it feel cold.

Question 20

What is an energy profile diagram?

Answer 20

An energy profile is a representation of a chemical reaction as a single energetic pathway as the reactants are transformed into products.

Question 21

Draw a exothermic energy profile diagram with these labels:
-Products
-Reactants
-Enthalpy change
-Transition state
-Activation energy

Answer 21

Answers on page 4

Question 22

Draw a endothermic energy profile diagram with these labels:
-Products
-Reactants
-Enthalpy change
-Transition state
-Activation energy

Answer 22

Answers on page 4

Question 23

Is enthalpy change written with the products or reactant for exothermic reactions

Answer 23

With the products because heat is being released

Question 24

Is enthalpy change written with the products or reactant for endothermic reactions

Answer 24

With the reactants because heat is being absorbed

Question 25

What is a dilute solution?

Answer 25

A dilute solution is a solution in which a small amount of solute is dissolved in a large amount of solvent.

Question 26

What is a concentrated solution?

Answer 26

A concentrated solution is a solution in which the amount of solute dissolved is more compared to the amount of solvent.

Question 27

What is reaction rate?

Answer 27

A measure of the rate at which reactants are consumed or products are formed

Question 28

What increases reaction rate?

Answer 28

-Increased temperature -Increased concentrations -Increased pressure -State of subdivision -Presence of a catalyst

Question 29

What is a catalyst?

Answer 29

Any substance that increases the rate of a reaction without itself being consumed

Question 30

What does collision theory explain?

Answer 30

Why different reactions occur at different rates, and suggests ways to change the rate of a reaction

Question 31

According to collision theory, what conditions must be met for a chemical reaction to occur?

Answer 31

-The reacting particles must collide -The reacting particles must collide with sufficient energy -The reacting particles must collide with the correct orientation

Question 32

What is a transition state?

Answer 32

It is the highest potential energy state for a reaction It is a point in the reaction where new bonds are forming and the original bonds are breaking

Question 33

What is activation energy?

Answer 33

The minimal amount of energy required to form the transition state

Question 34

How does increasing the concentration increase reaction rate?

Answer 34

Increased concentration will increase the reaction rate because there are more reactant particles in a given volume, which according to collision theory, this leads to more frequent collisions, increasing the chances of successful collisions with sufficient energy and correct orientation, which speeds up the reaction. Flashcard version

Question 35

How does increasing the temperature increase reaction rate?

Answer 35

Increasing temperature increases the reaction rate because particles gain more kinetic energy. According to collision theory, this results in more frequent collisions and a greater proportion of particles having energy equal to or greater than the activation energy, increasing the number of successful collisions.

Question 36

How does increasing the gas pressure increase reaction rate?

Answer 36

Increasing the pressure of a gas increases the reaction rate because it compresses gas particles into a smaller volume, increasing their concentration. This leads to more frequent collisions, raising the chance of successful collisions as described by collision theory.

Question 37

How does increasing the state of subdivision increase reaction rate?

Answer 37

In heterogeneous reactions, increasing the surface area of a solid reactant allows more collisions to occur at the surface boundary between phases. Since reactants can only collide at this boundary, a larger surface area leads to more frequent collisions, increasing the rate of reaction according to collision theory.

Question 38

How does a catalyst increase the reaction rate?

Answer 38

A catalyst increases the reaction rate by providing an alternative reaction pathway with a lower activation energy. According to collision theory, this means more collisions occur with enough energy to be successful, increasing the reaction rate without being used up.