Calculate ∆H° for the following combustion reaction from the data given in the table below.
SiH4 (g) + 3 O2 (g) → SiO2 (s) + 2 H2O ()
To calculate ∆H° for the combustion reaction of SiH4, we need to use the enthalpies of formation of the reactants and products.
The enthalpies of formation for the given substances are as follows:
SiH4 (g): -161.8 kJ/mol
SiO2 (s): -911.7 kJ/mol
H2O (): -285.8 kJ/mol
The enthalpy of formation of O2 (g) is by definition 0.
Using these values, we can calculate ∆H° for the combustion reaction:
Products: (2 mol H2O)(-285.8 kJ/mol) + (1 mol SiO2)(-911.7 kJ/mol) = -1483.3 kJ
Reactants: (1 mol SiH4)(-161.8 kJ/mol) + (3 mol O2)(0 kJ/mol) = -161.8 kJ
∆H° = Σ(Products) - Σ(Reactants)
∆H° = -1483.3 kJ - (-161.8 kJ)
∆H° = -1483.3 kJ + 161.8 kJ
∆H° = -1321.5 kJ
Therefore, the standard enthalpy change (∆H°) for the combustion reaction of SiH4 is -1321.5 kJ.