Definition T5

Question 1

Enthalpy change of formation

Answer 1

Heat changed when one molecule of compound is formed from its element at their standard state, under standard condition (298K, 1 atm)

Question 2

Enthalpy change of combustion

Answer 2

Heat changed when one molecule of compound is burnt in excess oxygen in their standard state under standard condition (298K, 1 atm)

Question 3

Hess’ Law

Answer 3

The enthalpy change of a reaction depends only on the initial and final state and independent on the path followed.

Question 4

Enthalpy change of neutralisation

Answer 4

Heat change when 1 mole of water is formed when acid reacts with base under standard condition (298k, 1 atm)

Question 5

Enthalpy change of atomisation

Answer 5

Heat change when 1 mole of gaseous atom is formed from their element at their standard state under standard condition (298k, 1 atm)

Question 6

Enthalpy change of solution

Answer 6

Heat change when excess of water is added to 1 mol of substance so there is no further heat change if more water is added to the solution under standard condition (298k, 1 atm)

Question 7

Enthalpy change of hydration

Answer 7

Heat change when 1 mol of gaseous ion dissolved in excess of water under standard condition (298k, 1 atm)

Question 8

Enthalpy change of reaction

Answer 8

Heat change in a reaction, for the number of mol given in the equation

Question 9

Bond energy

Answer 9

Energy needed to break one mole of covalent bond between 2 atoms in gaseous state.