Types of ΔH Values

Question 1

What are the 4 types of ΔH (Heat of Reaction)

Answer 1

1. Heat of Solution
2. Heat of Neutralisation
3. Heat of Vaporisation
4. Heat of Combustion

Question 2

Describe Heat of Solution including properties

Answer 2

When a mole of any substance is dissolved in water:
* Can be exothermic or endothermic

Question 3

Describe Heat of Neutralisation including properties

Answer 3

When an acid reacts with a base to from a mole of water:
* Is generally exothermic

Question 4

Describe Heat of Vaporisation including properties

Answer 4

When a mole of liquid is converted to a gas:
* Is always endothermic

Question 5

Describe Heat of Combustion including properties

Answer 5

When a substance burns in oxygen, in terms oof given equation:
* is always exothermic

Question 6

What does Molar Heat of Combustion mean?

Answer 6

Heat of Combustion for kJ/mol

Question 7

What is an alternative definition for Heat of Combustion?

Answer 7

The heat energy released when a specific amount of substance undergoes complete combustion

As always exothermic, can talk about heat being released

Question 8

Why is Heat of Combustion important in VCE Chemistry?

Answer 8

Allows for the comparison between different fuels.

Question 9

Why might Heat of Combustion be calculated per gram or per litre instead of per mole?

Answer 9

As fuel is purchased in real world by mass or volume

Question 10

Alarm Bell! Why does ΔH for Heat of Combustion not have a negative sign?

Answer 10

As for VCAA purposed, Heat of Combustion does not need negative sign as they are all considered exothermic.
Must write negative sign for thermochemical equation though!