Topic 8- Energetics I

Question 1

What is meant by the standard enthalpy change of formation?

Answer 1

The enthalpy change when one mole of a substance is formed from its elements in their standard states at 100kPa and 298K

Question 2

What is Hess’s Law

Answer 2

He states that the enthalpy change of a reaction is independent of the path taken provided the initial and final conditions remain the same

Question 3

What direction do the arrows go if there is data for standard enthalpy of formation?

Answer 3

Arrows go up

Question 4

What is the standard enthalpy change of neutralisation?

Answer 4

The enthalpy change when one mole of water is produced by the neutralisation of an acid and an alkali at 100kPa and 298K

Question 5

What is the enthalpy change of combustion?

Answer 5

The enthalpy change when one mole of a substance is completely burned in oxygen at 100kPa and 298K

Question 6

What is bond enthalpy?

Answer 6

The enthalpy change when one mole of a bond in the gaseous state is broken

Question 7

What is meant by mean bond enthalpy?

Answer 7

The enthalpy change when one mole of a bond, averaged out over many different molecules, is broken

Question 8

What is the standard enthalpy change of reaction?

Answer 8

The enthalpy change when the number of moles of substances in the equation as written react

Question 9

What is an exothermic process?

Answer 9

When heat energy is transferred from the system to the surroundings

Question 10

What is an endothermic process?

Answer 10

When heat is transferred from the surroundings to the system