Reactivity 1.1

Question 1

In terms of kinetic energy, define temperature

Answer 1

The average kinetic energy of the particles

Question 2

State the units used to measure heat

Answer 2

Joule OR J

Question 3

During a chemical reaction, state the name of the contents inside the reaction vessel

Answer 3

System

Question 4

During a chemical reaction, state the name of the contents outside the reaction vessel

Answer 4

Surroundings

Question 5

Describe the transfer of matter and energy during a chemical reaction in an open system

Answer 5

Both energy and matter can be exchanged with the surroundings

Question 6

Describe the transfer of matter and energy during a chemical reaction in a closed system

Answer 6

Mass cannot be exchanged with the surroundings, although energy can be exchanged with the surroundings

Question 7

Describe the transfer of matter and energy during a chemical reaction in an isolated system

Answer 7

Both energy and matter cannot be exchanged with the surroundings

Question 8

In terms of energy transfer, define an exothermic reaction

Answer 8

Heat energy is transferred from the system to the surroundings during a chemical reaction

Question 9

In terms of energy transfer, define an endothermic reaction

Answer 9

Heat energy is transferred from the surroundings to the system during a chemical reaction

Question 10

Describe how the temperature of the surroundings changes during an exothermic chemical reaction

Answer 10

Increases

Question 11

Describe how the temperature of the surroundings changes during an endothermic chemical reaction

Answer 11

Decreases

Question 12

State the symbol given to enthalpy

Answer 12

H - must be capital

Question 13

State the symbol given to enthalpy change

Answer 13

ΔH - must be a capital

Question 14

State the name of the term that is the total amount of chemical energy in a set amount of a chemical substance

Answer 14

Enthalpy

Question 15

State the units of measurement for enthalpy

Answer 15

kJ mol⁻

Question 16

Describe how the temperature of the system changes during an exothermic chemical reaction

Answer 16

Decreases

Question 17

Describe how the temperature of the system changes during an endothermic chemical reaction

Answer 17

Increases

Question 18

Describe the enthalpy change during an exothermic reaction

Answer 18

Enthalpy change is negative

Question 19

Describe the enthalpy change during an endothermic reaction

Answer 19

Enthalpy change is positive

Question 20

Describe the difference in potential energy between reactants and products during an exothermic reaction

Answer 20

The reactants have higher potential energy than the products

Question 21

Describe the difference in potential energy between reactants and products during an endothermic reaction

Answer 21

The reactants have lower potential energy than the products

Question 22

State the name of the label for the y-axis of an energy profile diagram

Answer 22

Potential energy

Question 23

State the name of the label for the x-axis of an energy profile diagram

Answer 23

Reaction coordinate

Question 24

In terms of bonds, describe a transition state

Answer 24

A stage of the reaction where all chemical bonds are both partially broken and formed

Question 25

State the name of the state found at the peak of the energy profile diagram

Answer 25

Transition state

Question 26

Define activation energy

Answer 26

The minimum energy required for reactants to collide successfully begin to react

Question 27

Describe how to label the activation energy on an energy profile diagram

Answer 27

Draw an arrow from the potential energy of the reactants to the transition state

Question 28

State the symbol used to represent activation energy

Answer 28

Ea

Question 29

Describe how to label the enthalpy change on an energy profile diagram

Answer 29

Draw an arrow from the potential energy of the reactants to the potential energy of the products

Question 30

State the greek symbol that is used to represent an enthalpy change under standard conditions and states

Answer 30

Theta OR θ

Question 31

Define the standard enthalpy of reaction

Answer 31

The enthalpy change when the reactants in the stoichiometric equation react to give the products under standard conditions in their standard states

Question 32

State the standard pressure for an enthalpy change

Answer 32

100 kPa

Question 33

State the standard concentration for an enthalpy change

Answer 33

1.00 mol dm⁻³

Question 34

In calorimetry, state the name of the term with the symbol q

Answer 34

Heat transferred

Question 35

In calorimetry, state the name of the term with the symbol m

Answer 35

Mass of the water or solution

Question 36

In calorimetry, state the name of the term with the symbol c

Answer 36

Specific heat capacity

Question 37

Describe how to convert heat transferred (q) to enthalpy (H)

Answer 37

Divide by the amount, in moles, of the substance

Question 38

In calorimetry, explain why the true maximum temperature may never be reached

Answer 38

The reaction will be losing heat to the surroundings as the reaction begins and moves towards completion

Question 39

In calorimetry, explain how extrapolation can be used to determine the maximum temperature

Answer 39

Extrapolate the cooling section of the graph until the extrapolated line intersects the time when the reactant was added

Question 40

In calorimetry, describe the assumption for the rate of cooling

Answer 40

Rate of cooling is constant

Question 41

In calorimetry, describe TWO assumptions when using a solution

Answer 41

The solution has the same specific heat capacity and density as pure water

Question 42

State the density of water

Answer 42

1.00 g cm⁻³

Question 43

Explain why combustion of N₂ is an endothermic reaction

Answer 43

The triple bond in the nitrogen molecule requires a large amount of energy to break, therefore the energy required to break all the bonds is greater than the energy released forming all the new bonds