B. The heat of reaction for the process described in (a) can be determined by applying Hess's law. The heats of reaction shown in the table below can be obtained
experimentally or looked up in tables of enthalpy data. Which two of these heats of
reaction would be the easiest and safest to measure in the laboratory, and which two are
better obtained through reference sources? Why? Hint: Consider whether a reaction
takes place in aqueous solution or instead involves noxious gases.
Reaction
Heat of reaction
NH3(g) → NH3(aq)
AH= -34.64 kJ/mol
NH3(aq) + HCl(aq) → NH4+ (aq) + Cl(aq)
AH= -51.6 kJ/mol
HCI(g) → HCl(aq)
AH = -75.14 kJ/mol
AH = +14.8 kJ/mol
NH4Cl(s) → NH4+(aq) + Cl(aq)