已知下列热化学方程式: ①CaCO3(s)═CaO+CO2(g)△H=+177.7kJ
②C(s)+H2O(s)═CO(g)+H2(g)△H=﹣131.3kJ•mol﹣1
③ H2SO4(1)+NaOH(1)═ Na2SO4(1)+H2O(1)△H=﹣57.3kJ•mol﹣1
④C(s)+O2(g)═CO2(g)△H=﹣393.5kJ•mol﹣1
⑤CO(g)+ O2(g)═CO2(g)△H=﹣283kJ•mol﹣1
⑥HNO3(aq)+NaOH(aq)═NaNO3(aq)+H2O(1)△H=﹣57.3kJ•mol﹣1
⑦2H2(g)+O2(g)═2H2O(1)△H=﹣517.6kJ•mol﹣1