Chapter 9

Question 1

What is activation energy?

Answer 1

Ea is the minimum energy required for a reaction to take place ( Energy required to break bonds = Energy barrier)

Question 2

What is the Standard enthalpy change of reaction? (ΔH°)

Answer 2

The enthalpy change associated with a stated equation in molar quantities shown in the chemical equation under standard conditions

Question 3

What is the standard enthalpy change of formation (ΔfH°)

Answer 3

The enthalpy change associated with the formation of 1 mole of a compound from its elements under standard conditions

Question 4

What is the standard enthalpy change of combustion (ΔcH°)

Answer 4

Enthalpy change associated with the complete combustion of 1 mole of a substance under standard conditions

Question 5

what is the standard enthalpy change of neutralisation (ΔneutH°)

Answer 5

Enthalpy change associated with the formation of 1 mole of water from a neutralisation reaction between an acid and a base, under standard conditions

Question 6

How do you calculate the heat energy (q) transferred between the system and the surroundings?

Answer 6

q = mcΔT

Question 7

What is an average bond enthalpy?

Answer 7

The energy required to break one mole of a specified type of bond in a gaseous molecule

Question 8

What is the enthalpy change when breaking bonds?

Answer 8

Breaking bonds is endothermic, so the enthalpy is positive

Question 9

What is the enthalpy change when forming bonds?

Answer 9

Forming bonds is exothermic, so the enthalpy is negative

Question 10

What is Hess’ Law?

Answer 10

If a reaction can take place by two routes, and the starting and finishing conditions are the same, the total enthalpy change is the same for each route