Nitric acid, which is among the top 15 chemicals produced in the United States, was first prepared over 1200 years ago by heating naturally occurring sodium nitrate (called saltpeter) with sulfuric acid and collecting the vapors produced. Calculate ΔH°rxn for this reaction. ΔH°f [NaNO3(s)] = -467.8 kJ/mol; ΔH°f [NaHSO4(s)] = -1125.5 kJ/mol; ΔH°f [H2SO4(l) = -814.0 kJ/mol; ΔH°f [HNO3(g)] = -135.1 kJ/mol.