Absolute value describes the distance of a number on the number line from 0 without considering which direction from zero the number lies. The absolute value of a number is never negative. The absolute value of 5 is 5.
Explanation:
The heat energy released when new bonds are made between the ions and water molecules is known as the hydration enthalpy of the ion. The hydration enthalpy is the enthalpy change when 1 mole of gaseous ions dissolve in sufficient water to give an infinitely dilute solution. Hydration enthalpies are always negative.
Heat of hydration or enthalpy of hydration of ions corresponds to the heat that is released by hydration of one mole of ions at a constant pressure. The more the ion is hydrated, the more heat is released. Degree of hydration depends on the size and charge of ion.