Thermodynamics Flashcards
The standard molar enthalpy of formation, ▲fH
The standard molar enthalpy of formation is the enthalpy change when ONE MOLE OF A COMPOUND IS FORMED FROM ITS CONSTITUENT ELEMENTS under standard conditions, all reactants and products in their standard states.
The standard molar enthalpy change of combustion, ▲cH
The standard molar enthalpy change of combustion is the enthalpy change when ONE MOLE OF A SUBSTANCE IS COMPLETELY BURNT IN OXYGEN.
The standard enthalpy of atomisation, ▲atH
The standard enthalpy of atomisation is the enthalpy change WHICH ACCOMPANIES THE FORMATION OF ONE MOLE GASEOUS ATOMS FROM THE ELEMENT in its standard state under standard conditions.
First ionisation energy, ▲iH
First IE is the standard enthalpy change when ONE MOLE OF GASEOUS ATOMS IS CONVERTED TO A MOLE OF GASEOUS IONS, EACH WITH A SINGLE POSTITIVE CHARGE.
Second ionisation energy
Second IE refers to the LOSS OF A MOLE OF ELECTRONS FROM A MOLE OF SINGLY POSITIVELY CHARGED IONS.
First electron affinity, ▲eaH
The first electron affinity is the standard enthalpy change when A MOLE OF GASEOUS ATOMS IS CONVERTED TO A MOLE OF GASEOUS IONS, EACH WITH A SINGLE NEGATIVE CHARGE.
E.g.
O(g) + e- —> O- (g)
Second electron affinity
Second ▲ eaH is the enthalpy change when A MOLE OF ELECTRONS IS ADDED TO A MOLE OF GASEOUS IONS EACH WITH A SINGLE NEGATIVE CHARGE TO FORM IONS WITH TWO NEGATIVE CHARGES.
E.g.
O- (g) + e- —> O^2- (g)
Lattice enthalpy of formation, ▲L H
Lattice enthalpy of formation is the standard enthalpy change when ONE MOLE OF A SOLID IONIC COMPOUND IS FORMED FROM ITS GASEOUS IONS
E.g.
Na+ (g) + Cl- (g) —> NaCl (s)
Lattice enthalpy of dissociation
Lattice enthalpy of dissociation, is the standard enthalpy change when ONE MOLE OF SOLID IONIC COMPOUND DISSOCIATED INTO ITS GASEOUS IONS.
Enthalpy of hydration, ▲hyd H
Enthalpy of hydration is the standard enthalpy change when 1 MOLE OF GASOUS IONS ARE CONVERTED INTO AQUEOUS IONS / AN AQUEOUS SOLUTION.
Enthalpy of solution, ▲sol H
enthalpy of solution is the standard enthalpy change when ONE MOLE OF SOLUTE DISSOLVES COMPLETELY IN SUFFICIENT SOLVENT TO FORM A SOLUTION IN WHICH THE MOLECULES OR IONS ARE FAR ENOUGH APART NOT TO INTERACT WITH EACH OTHER.
Mean bond enthalpy
mean bond enthalpy is the enthalpy change when ONE MOLE OF GASEOUS MOLECULES EACH BREAKS A COVALENT BOND TO FORM TWO FREE RADICALS, AVERAGED OVER A RANGE OF COMPOUNDS.
Overall entropy change equation
▲S total = ▲S products - ▲S reactants
Gibbs’s free energy equation
With units
▲G = ▲H - T ▲S
▲G = kJmol-1
T = Kelvin, K
What does ▲G value have to be for spontaneous reactions
▲G is negative for all spontaneous reactions.
This becomes true at a certain, specific temperature which can be found by putting ▲G equal to zero.
