define lattice enthalpy?
Answers
The lattice energy of a crystalline solid is a measure of the energy released when ions are combined to make a compound. It is a measure of the cohesive forces that bind ions. Lattice energy is relevant to many practical properties including solubility, hardness, and volatility.
Lattice enthalpy and lattice energy are commonly used as if they mean exactly the same thing - you will often find both terms used within the same textbook article or web site, including on university sites.
In fact, there is a difference between them which relates to the conditions under which they are calculated. However, the difference is small, and negligible compared with the differing values for lattice enthalpy that you will find from different data sources.
Unless you go on to do chemistry at degree level, the difference between the two terms isn't likely to worry you.