clc 
//initialisation of variables
HNaCl= -97.219 //kcal
HH2O= -68.3174 //kcal
HHcl= -39.713 //kcal
HNaOH= -112.108 //kcal
//CALCULATIONS
H298= HNaCl+HH2O-HHcl-HNaOH
//RESULTS
printf ('dH298= %.3f kcal ',H298)