Well, #"lattice enthalpy is the enthalpy associated with the "#
#"formation of one mole of an ionic solid from equiv quantites"#
#"of its constituent ions, with the reactant specified to be in the"#
#"gas phase."#
And thus, for the lattice enthalpy of #"sodium chloride"# we would interrogate the thermodynamics of the reaction:
#Na^(+)(g) + Cl^(-)(g) rarr NaCl(s) +Delta#,
where #Delta-="Lattice enthalpy."#
And while this is a hard measurement to make experimentally, there are enuff good thermodynamic data to allow the measurement by data from known experiments.
And #"hydration enthalpy"# is the #"enthalpy associated with the"#
#"formation of one mole of hydrated ions from one mole of"#
#"gaseous ions that undergo hydration to give aquated ions."#
#M^(+)(g) + "excess water"rarr M^(+)(aq) +Delta#
Again, the data are good enuff to allow recourse to tabulated measurements.
