Calculate the enthalpy change of formation for the following reactions using Hess's law, and the enthalpies of formation given in Figure 4:

Question

b) MgO +2HCl --> MgCl2 +H2O
c)NaOH+ HCl -->NaCl +H20

Figure4: the given enthalpies of formation compound values are:
Mg(OH)2 is 925kj mol-1

H2O is -286 kj mol-1
NaOH is -169 kj mol-1
MgO is -602 kjmol-1
HCl is -167 kjmol-1
MgCl2 is -641 kj mol-1
NaCl is -107 kjmol-1

Answer 1

This question isn't worded very well in my opinion but I think you want just the enthalpy for the reaction given. Those are
dHrxn = (n*dH products) - (n*dH reactants)
dHrxn = (1*MgCl2 + 1*H2O) - (1*MgO + 2*HCl)
dHrxn = [1*(-641) + 1*(-286)] - [1*(-602) + 2*(-167)] = ?