the energy required to break a mole of a covalent type of bond in a gaseous state averaged across a variety of compounds
reactants-products
kJ/mol
Limitation: average taken, they must be in their standard states
what is the standard enthalpy change of combustion
is the enthalpy change for the complete combustion of one mole of a substance in its standard state in excess oxygen under standard conditions
how to ensure no heat loss
polystyrene cup
enthalpy can't be measured directly
but enthalpy change can be measured through measuring temperature chang e
what is DHf
Standard enthalpy change of formation is the enthalpy change that occurs when one mole of the substance is formed from elements in their standard states
products-reactants
first ionization energy creates
psotivie ions
electron affinity creates
negative ions
what is lattice enthalpy
enthalpy change that occurs when one mole of solid ionic compound is separated into gaseous ions under standard conditions
what is enthalpy of atomization
one mole of gaseous atoms are formed from the element in its standard state
electron affinity
first is exothermic
second is endothermic
lattice enthalpy is increases as
ions get smaller
ions have higher charges
enthalpy change of solution
is the enthalpy change when one mole of a solute is dissolved in a solvent to infinite dilution under standard conditions
latttice+ hydration of ion + hydration of ion
enthalpy of hydration
exothermic and negative
strength of bonds between polar water molecules and the separated ions