Definition of untiring for English Language Learners. : working very hard with a lot of energy for a long time : never seeming to get tired.
Enthalpy is the heat content of a chemical system. The molar enthalpy of reaction (Hrxn) is the amount of heat transferred during a reaction. It is reported in kilojoules per mole of reactant. A reaction that produces heat is exothermic and has a negative Hrxn.A reaction that absorbs heat is endothermic and has a positive Hrxn.he molar enthalpy of reaction (Hrxn) is the amount of heat transferred during a reaction. It is reported in kilojoules per mole of reactant. A reaction that produces heat is exothermic and has a negative Hrxn. A reaction that absorbs heat is endothermic and has a positive Hrxn.
Yes, the enthalpy of hydration is always negative. Hydration enthalpy is the energy released when 1 mol of a substance is dissolved in a solvent. It is always negative, as bonds (e.g. dative, ion-dipole) are being formed. When the solvent is other than water, the process is referred to as solvation. The enthalpy of hydration is equal to the sum of three different energy transfer processes 1  : the lattice energy.  the enthalpy of hydration of the cation.