Calculate Delta H reaction

Question

Calculate the standard enthalpy change, ΔH°rxn, in kJ for the following chemical equation, using only the thermochemical equations below:

2SOCl₂(l) + O₂(g) → 2SO₂(g) + 2Cl₂(g)

Equations:		ΔH°rxn (kJ)
2Fe(s) + 3Cl2(g) → 2FeCl3(s)		-800
4Fe(s) + 3O2(g) → 2Fe2O3(s)		-1644.4
Fe2O3(s) + 3SOCl2(l) → 2FeCl3(s) + 3SO2(g)		-137.7

Answer 1

Reverse eq 1 & x2: 4FeCl3 ==> 4Fe + 6Cl2 ΔH = +1600

copy eq 2: 4Fe + 3O2 ==> 2Fe2O3 ΔH = -1644

copy eq 3 & x2: 2Fe2O3 + 6SOCl2 ==> 4FeCl3 + 6SO2 ΔH = -275

add all, cancel where appropriate, and add the ΔH values. Then divide all by thee to get

2SOCl2 + O2 ==> 2SO2 + 2Cl2 ΔH = -106kJ