What are #"lattice"# and #"hydration energies"#?

Question

Serenity Allen · Accepted Answer

Well, #"lattice enthalpy is..................."#

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."#

Even though it's a challenging measurement to make experimentally, there are enough reliable thermodynamic data available to support the measurement using information from previous studies.

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#

Once more, the data are sufficient to enable the use of tabulated measurements.

Olivia Anton · Answer

undefined "Lattice energy" refers to the energy released when ions in the gas phase come together to form a solid ionic compound. "Hydration energy" refers to the energy released when ions in the gas phase are surrounded by water molecules and form hydrated ions in solution.