Question

Consider the following information. • The lattice energy of NaCl is AHlattice = –788 kJ/mol. • The enthalpy of sublimation of Na is AHsub = 107.5 kJ/mol. • The first ionization energy of Na is IE1 = 496 kJ/mol. • The electron affinity of Cl is AHEA = -349 kJ/mol. • The bond energy of Cl, is BE = 243 kJ/mol. Determine the enthalpy of formation, AHf, for NaCl(s). AH= kJ/mol

Answer 1

Energy changes involved in the formation of Jonic Compound Nau: ď solid to sodium metal atous gets conver- gaseous sodium atau go by absorbing ted energy called sublimation energy, Na (s) - Nalg) , A Han = 107.5557ando Sub ③ Amount of euersy required to remove au electral from outer moxt shell of goseous Sodium atore is called Inization energy. Nacg, -é - Natcas IE, - 496 kJ/ml,

gaseous ch molecule dissociates to culorine ataus by abforbing energy Called Band dissociation Quey94 Cl2 - 21 , BE 243 kJ mot's Energy for Imole of cl ateuy - B.E 243 - 121.5 ks mort. D gaseous chlorine atau gains electron and Euergy released called electron Attivity - até -ci EA = -34915/ ul. 0 Imole of gaseous wat and Imole of a Ias come closer hold on to secuer to form lettice Naul and release eversy celled lattice euergy, Nat (g) +cirg) Nad lattice According to Hest law, the net heat ct reaction is equal to sum of Euergy changes involved in the reaction.

AH, (NOU) E A HAT JE, + B.Et = + EA + U. Sub - lattice everse) z) AHY (NAL) = 107.5 + 496+ 124.5 -349-788) KJ mol -412 kJ mot