Thermal Dynamic (Enthalpy)

Question 1

Define Enthalpy of Formation with an example equation (Na2O)

Answer 1

Enthalpy change 1 mol of a substance formed from constituent elements (standard states)
e.g 2Na (s) + 1/2 O2 (g) -> Na2O (s)

Question 2

Define Enthalpy of combustion with an example equation (CH4)

Answer 2

Enthalpy Change 1 mol complete combustion standard states
CH4 + 2O2 -> CO2 + 2H2O

Question 3

Define 1st Ionisation Enthalpy with an example equation (Mg)

Answer 3

Enthalpy Change each atom in 1 mol of (g) atoms lose 1 e- from 1 mol of (g) ions
Mg(g) -> Mg+(g) + e-

Question 4

Define 2nd Ionisation Enthalpy with an example equation (Mg+)

Answer 4

Enthalpy Change each ion in 1 mol of (g) 1+ ions loses 1 e- to form 1 mol of (g) 2+ ions
Mg+ (g) -> Mg2+ + e-

Question 5

Define the 1st Electron Affinity with an example equation (O2)

Answer 5

Enthalpy change each atom in 1 mol of (g) atoms gains 1 e- to form 1 mol of (g) 1- ions
O(g) + e- -> O-(g)

Question 6

Define the 2nd Electron Affinity with an example equation (O-)

Answer 6

Enthalpy change each ion in 1 mol (g) 1- ions gains 1 e- to form 1 mol of (g) 2- ions
O-(g) + e- -> O2-(g)

Question 7

Define Enthalpy of Atomisation with an example equation (I)

Answer 7

Enthalpy change 1 mol of (g) atoms produced from element in standard states
1/2 I2 (s) -> I (g)

Question 8

Define Bond dissociation enthalpy with an example equation (I)

Answer 8

Enthalpy change 1 mol of covalent bods broken in (g) state
I2 (g) -> 2I (g)

Question 9

Define Lattice enthalpy of formation with an example equation (MgCl2)

Answer 9

Enthalpy change 1 mol of a (s) ionic compound formed from constituent ions in (g) phase
Mg2+ (g) + 2Cl- (g) -> MgCl2 (s)

Question 10

Define Lattice enthalpy of dissociation with an example equation

Answer 10

Enthalpy change 1 mol of (s) ionic compound broken up into constituent ions in (g) phase