The standard molar enthalpy of formation for ammonium chloride (aq), NH₄Cl(aq), is -299.66 kJ/mol.

This value is often found in thermodynamic tables.

Keep in mind that the enthalpy of formation is the enthalpy change that occurs when one mole of a substance is formed from its constituent elements in their standard states under standard conditions (298 K and 1 atm).