Enthalpy Terms

Question 1

What is thermodynamics?

Answer 1

Branch of physical chemistry focusing on energy in a chemical system: reactants and products

Question 2

What can energy be changed into?

Answer 2

Different types of energy

Question 3

How must chemists carry out meaningful calculations?

Answer 3

All values must be measured under standard conditions

Question 4

What are standard conditions?

Answer 4

• 100 kPa/1 bar
• 298°K/25°C
• Given plimsoll line symbol (⦵)

Question 5

What does it mean that all substances are in their standard states?

Answer 5

In most stable form

Question 6

What is the enthalpy change of a reaction?

Answer 6

Energy change associated with a given reaction

Question 7

What does a thermodynamic equation include?

Answer 7

Both balanced chemical equation and enthalpy data

Question 8

What is enthalpy change of formation?

Answer 8

Energy change taking place when 1 mole of a compound is formed from its constituent elements in their standard state under standard conditions

Question 9

What may you need to do when writing a thermodynamic equation?

Answer 9

Use fractions to balance equation, as you must ensure there’s only 1 mole of product

Question 10

What is the standard enthalpy change of formation of an element in its standard states?

Answer 10

0 kJ mol⁻¹

Question 11

Why is the standard enthalpy change of formation of an element in its standard states 0 kJ mol⁻¹?

Answer 11

According to definition there’s no change (as no compound is formed), so no energy is released or taken in

Question 12

What is enthalpy change of combustion?

Answer 12

Energy change taking place when 1 mole of a substance is completely combusted

Question 13

What is enthalpy change of neutralisation?

Answer 13

Energy change associated with formation of 1 mole of water from a neutralisation reaction