Thermodynamics Flashcards
Enthalpy of Formation
- the enthalpy change when 1mole is formed
- from elements in their standard states
- and all products and reactants in their standard states
what is the standard enthalpy of formation of an element?
0
Enthalpy of Combustion
- enthalpy change when 1 mole is combusted
- completely in oxygen
- and all products and reactants are in their standard states
Ethalpy change of atomisation of an element
- enthalpy change when of 1 mole of gaseous atoms
- is formed
- from an element in its standard state and standard under conditions
First Ionisation Energy Enthalpy
the enthalpy change when 1 mole of +1 gaseous ions is formed from 1 mole of gaseous atoms.
(electron loss)
First Election Affinity Enthalpy
the enthalpy change when 1 mole of gaseous -1 ions is formed from 1 mole of gaseous atoms
(electron gain)
Lattice Enthalpy of Formation
enthalpy change when 1 mole of a solid ionic compound is formed from its gaseous ions under standard conditions
Lattice Enthalpy of Dissociation
enthalpy change when 1 mole of a solid ionic compound is dissociated into 1 mole of gaseous ions, under standard conditions
Enthalpy of Hydration
enthalpy change when 1 mole of aqueous ions is formed from 1 mole of gaseous ions
Enthalpy of Solution
enthalpy change when 1 mole of solute is dissolved in enough solvent that no further enthalpy change occurs on further dilution
Mean Bond Enthalpy
enthalpy change when 1 mole of gaseous molecules breaks a covalent bond to form 2 free radicals
Hess’ Law
the total energy (or enthalpy) change for a chemical reaction is the same whatever route is taken.
provided that the initial and final conditions are the same
Born-Haber
is a thermocheical cycle that includes all the enthalpy changes involved in the formation of an ionic compound.
exothermic reactions have a … enthalpy value
negative
because heat energy is given out
endothermic reactions have a …. enthalpy value
positive
because heat energy is taken in
Second Ionisation Energy
the enthalpy change when 1 mole of gaseous +2 ions is formed from 1 mole of gaseous +1 ions
Second Electron Affinity
the enthalpy change when 1 mole of gaseous -2 ions is formed from 1 mole of gaseous -1 ions
Enthalpy change of atomisation of a compound
enthalpy change when 1 mole of a compound, in its standard state, is converted to gaseous atoms
Bond Dissociation Enthalpy
enthalpy change when all the bonds of the same type in 1 mole of gaseous molecules are broken
Entropy
the measure of the number of ways that particles can be arranged and the number of ways that the energy can be shared out between the particles
If the entropy value is large and positive, the level of disorder is
high
