Please help me with the enthalpy of combustion of a metal

1)Mg+2HCl- MgCl2+H2
2)MgO+2HCl-MgCl2+H2O
3)2Mg+O2-2MgO

I need to find the experimental enthalpy of combustion in kJ and the theoretical enthalpy of it.

Question

Please help me with the enthalpy of combustion of a metal

1)Mg+2HCl-> MgCl2+H2
2)MgO+2HCl->MgCl2+H2O
3)2Mg+O2->2MgO

I need to find the experimental enthalpy of combustion in kJ and the theoretical enthalpy of it.

primeralph · Answer

You need to find the individual enthalpies. You should be given or so.

anonymous · Answer

@primeralph  it was not given :(...

primeralph · Answer

Well, maybe you should use standard values. Google the enthalpies.

anonymous · Answer

@primeralph  it says i need to use the Hess's law??

primeralph · Answer

Yeah, but you'll need numbers to plug in.

anonymous · Answer

find the enthalpies of formation for each compound (elements in their pure, most stable form are zero so you can just ignore Mg and O2)