Thermodynamics

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  • Created by: Dom
  • Created on: 04-06-13 12:05

Enthalpy of Formation

One mole of COMPOUND is formed from its constituent ELEMENTS

Delta Hf = products - reactants

C(s)+ O2 (g) - CO2 (g)

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Combustion

Enthalpy change when one mole of SUBTANCE undergoes COMPLETE COMBUSTION in EXCESS oxygen.

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Atomisation

Enthalpy change when One mole of GASEOUS ATOMS is produced from an ELEMENT.

Na (s) => Na (g)

1/2 H2 (g) => H (g)

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Ionisation

Energy Required to remove one mole of Electrons from one mole of GASEOUS ATOMS.

Produces a 1+ ion.

M (g) => M+ (g) + e-

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Electron Affinity

Enthalpy change when one mole of GASEOUS ATOMS gains ONE ELECTRON per ATOM 

X (g) + e- =>X-


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Hydration

When one mole of GASEOUS IONS is converted into AQUEOUS IONS 

hydration = -lattic enthalpy - sum of solution enthalpies

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Solution

One mole of SOLUTE DISSOLVES in a LARGE AMOUNT of WATER enough to prevent IONS INTERACTING

Solution = -lattice enthalpy + sum of hydration enthalpies

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Lattice enthalpy

Enthalpy change when M+ (g) + X- (g) => MX(s) occurs 

Exothermic in forwards direction. 

Conditions 298K

100kPa

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Bond dissociation

One mole of COVALENT BOND is BROKEN in the GASEOUS STATE forming 2 FREE RADICALS


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Born-Harber Cycle

 ELECTRON AFFINITY

Atomisation of Cl 

Ionisation of Sodium                                                                             Lattice enthalpy of NaCl

Atomisation of Sodium 

Formation of NaCl 

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