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