3.4 Definitions

Question 1

What is the definition of Δf H°

Answer 1

The energy required to produce one mole of product from its constituent atoms in their standard states at standard conditions.

Question 2

What is the definition of: Δc H°

Answer 2

The enthalpy of combustion is the energy required to react 1 mol of fuel with oxygen under standard conditions.

Question 3

What is the definition of: Δvap H°

Answer 3

The enthalpy of vaporisation is the energy required to convert 1 mol of a liquid into 1 mol of gas at the boiling point under standard conditions.

Question 4

What is the definition of: Δfus H°

Answer 4

The enthalpy of fusion is the energy required to convert 1 mol of a solid to 1 mol of liquid at the melting point under standard conditions.

Question 5

What is the definition of: Δsub H°

Answer 5

The enthalpy of sublimation is the energy required to convert 1 mol of a solid to 1 mol of gas at the sublimation point under standard conditions.

Question 6

What is the definition of: entropy

Answer 6

ΔS

Entropy is a measure of disorder in a system.

Question 7

What is the definition of: electronegativity

Answer 7

Electronegativity is a measure of the attraction that an atom has for a pair of bonding electrons.

Question 8

What is the definition of: first ionisation energy

Answer 8

First ionisation energy is the energy needed to remove 1 mol of electrons from 1 mol of gaseous atoms.

Question 9

What is the overall trend in electronegativity?

Answer 9

Electronegativity increases across the period and decreases down the groups. (Exactly the same as First Ionisation Energy).

Question 10

What is the overall trend in first ionisation energy?

Answer 10

First Ionisation Energy increases across the period and decreases down the groups. (Exactly the same as electronegativity).