TOPIC 8 - Energetics I

Question 1

What is the enthalpy change of a reaction?

Answer 1

The change in heat energy in a reaction at constant pressure measured in kJ/mol.

Question 2

What does this symbol mean?

Answer 2

Enthalpy change with standard conditions (298K, 100kPa) and all elements in standard states.

Question 3

What are endothermic reactions?

Answer 3

Question 4

How does the energy diagram for an endothermic reaction look like?

Answer 4

Question 5

What are exothermic reactions?

Answer 5

Question 6

How does the energy diagram for an exothermic reaction look like?

Answer 6

Question 7

What does this symbol mean?

Answer 7

Question 8

What does this symbol mean?

Answer 8

Question 9

What does this symbol mean?

Answer 9

Question 10

What does this symbol mean?

Answer 10

Question 11

Is breaking bonds endothermic or exothermic?

Answer 11

Question 12

Is making bonds endothermic or exothermic?

Answer 12

Question 13

What is the equation for enthalpy change, in terms of energy from breaking/making bonds?

Answer 13

Question 14

What is bond enthalpy?

Answer 14

Question 15

What is the equation for measuring the heat energy change in a calorimeter?

Answer 15

Question 16

How can the enthalpy of a reaction be calculated using a calorimeter?

Answer 16

1. Calculate the amount of energy.
2. Divide it by the number of moles.

Question 17

Why is a calorimetry experiment with solutions often carried out in a polysterene cup?

Answer 17

To prevent heat loss.

Question 18

What is Hess’ law?

Answer 18

Question 19

When given enthalpy of formation, which Hess cycle would you draw?

Answer 19

Question 20

When give enthalpy of combustion, which Hess cycle would you draw?

Answer 20