Consider the following reaction and the given thermodynamic data at 25°C.
MgO(s) + 2HCl(aq) ? MgCl2(aq) + H2O(1)
Compound MgO(s) HCl(aq) MgCl2(aq) H2O(1)
?H°f / kJ mol?¹ -601.8 -167.16 -641.6 -285.8
(a) Define the term standard enthalpy change of formation, ?H°f.
(b) Write a thermochemical equation for ?Hf [MgCl2(aq)].
(c) Calculate ?H°rxn at 25°C.
(d) Under constant pressure situation, what is the relationship between heat of reaction, q, and the enthalpy change of reaction, ?H°rxn. Explain your answer by calculations.