Use values of standard enthalpies of formation to calculate the enthalpy change for the reaction below:

Question

Use values of standard enthalpies of formation to calculate the enthalpy change for the reaction below: 

NH3(g)+HCl(g) → NH4Cl(s)

Give the quantity and unit (kJ) and don't forget the + or - sign. 

Answer 1

Look up values for standard enthalpy of formation for NH4Cl(s) and for NH3(g). Subtract the value for NH4Cl from that for NH3(g) to get your answer. As before, the concept is PRODUCTS - REACTANTS