7.4 Enthalpy Flashcards
Enthalpy (H)
a thermodynamic quantity equivalent to the total heat content of a system
enthalpy is a ______ (state/process) function
state function
The standard heat/enthalpy of formation
enthalpy required to produce one mole of a compound from its elements in their standard states
the standard heat/enthalpy of reaction
the enthalpy change accompanying a reaction being carried out under standard conditions
Hess’s law
the enthalpy change associated with a reaction carried out in multiple steps is equal to the sum of the enthalpy change for each individual step
Hess’s law applies to ANY state function, including entropy and Gibb’s free energy
Bond dissociation energy:
the average energy required to break a particular type of bond between atoms in the gas phase
bond dissociation energy units
kJ / mols of bonds broken
Bond enthalpies
the averages of the bond energies for the same bond in many different compounds
Bond formation energy
energy released when bonds are formed
same magnitude as bond dissociation energy, negative value
equation for the enthalpy for a given reaction
Standard heat of combustion
the enthalpy change associated with the combustion of a fuel
