Thermodynamics ( A-level )

Question 1

What does Hess’s law state?

Answer 1

The enthalpy change for a reaction is independent of the route taken by the reactants

Question 2

What is the standard enthalpy of an element?

Answer 2

Zero

Question 3

Define standard enthalpy of atomisation

Answer 3

the enthalpy change when of gaseous compound is formed from a compound in its standard state

Question 4

Define first electron affinity

Answer 4

Enthalpy change when one mole of gaseous atom gains one mole of electron to form one mole of a gaseous 1- ions

Question 5

Define second affinity

Answer 5

Enthalpy change when one mole of gaseous 1- ion gains one mole of electron to form one mole of gaseous 2- ion

Question 6

Define lattice enthalpy of formation

Answer 6

Enthalpy change when one mole of a solid ionic compound is formed from its consistuents ions in their gaseous state

Question 7

Define lattice enthalpy of dissociation

Answer 7

Enthalpy change when mole of a solid ionic compound dissociates into its consistuent ions in their gaseous state

Question 8

Define enthalpy of hydration

Answer 8

Enthalpy change when one mole of gaseous ions dissolves completely in water to form a infinitvely dilute solution

Question 9

Define enthalpy of solution

Answer 9

Enthalpy change when one mole of a solid ionic compound dissolves completely in water to form a infinitvely dilute solution

Question 10

Define mean bond dissociation enthalpy

Answer 10

Enthalpy change when one mole of covalent is broken, with all species in their gaseous state