Given....#2Mg(s) + O_2(g) rarr 2MgO(s)# #; DeltaH_"rxn"=-1203*kJ*mol^-1# What enthalpy is associated with the combustion of FOUR moles of magnesium metal?

1 Answer
anor277
Jun 12, 2017

#DeltaH=-2406*kJ...........#

Explanation:

#2Mg(s) + O_2(g) rarr 2MgO(s)# # DeltaH_"rxn"=-1203*kJ*mol^-1#

Enthalpy terms are written per mole of reaction as written. We combust 4 moles of magnesium metal, and should therefore generate #2xx-1203*kJ=-2406*kJ#.

Note that given these data we could write #DeltaH_f^@(MgO)=-601.5*kJ#. Why?

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