How do I write new reactions that include ΔH as a reactant or product for NaCl, KCl, and CaCl2

Question

salts: Nacl, KCl, CaCl2

Answer 1

If the reaction is exothermic, include heat as a product, either by simply writing heat or including the delta H as an amount of heat produced. As a product of the exothermic reaction, even though the delta H would be negative, you would write the product as a positive value since it is produced. For instance, for the dissolution of CaCl₂ in water, where the heat of solution is -89.2 kJ/mol, you would write:

 

CaCl_{2 (s)} -------> Ca⁺²_(aq) + 2 Cl^-_(aq) + 89.2 kJ

 

If dissolving is an endothermic reaction, heat is consumed, as in, for instance, the dissolution of NaCl or KCl, the heat or delta H would be included as a reactant.  For instance, the heat of solution for KCl is 17 kJ/mol, and you would write:

 

 17 kJ   +  KCl_(s) ----> K⁺_(aq)  +  Cl^-_(aq)