Asam Sulfat (H2SO4) dapat di produksi menurut reaksi SO3 + H2O → H2SO4 ∆Hr = XkJ jika diketahui ∆Hf SO3 = -396 kJ, ∆Hf H2O = -286 kJ dan ∆Hf H2SO4 = -814 kJ ma

SO3 + H2O → H2SO4 ∆Hr = X kJ/mol
∆Hf SO3 = -396 kJ/mol
∆Hf H2O = -286 kJ/mol
∆Hf H2SO4 = -814 kJ/mol

∆Hr = [ ∆Hf produk ] - [ ∆Hf reaktan ]
X = ( ∆Hf H2SO4 ) - ( ∆Hf SO3 + ∆Hf H2O )
X = -814 - (-396 - 286)
X = - 132 kJ/mol