Question

【題目】現(xiàn)有三個熱化學方程式：

(1)CH3COOH(l)＋2O2(g)===2CO2(g)＋2H2O(l) ΔH1＝－870.3 kJ/mol

(2)C(s)＋O2(g)===CO2(g) ΔH2＝－393.5 kJ/mol

(3)H2(g)＋O2(g)===H2O(l) ΔH3＝－285.8 kJ/mol

則反應(yīng)2C(s)＋2H2(g)＋O2(g)===CH3COOH(l)的反應(yīng)熱為(　　)

A. －488.3 kJ/mol B. ＋488.3 kJ/mol

C. －2 228.9 kJ/mol D. ＋191 kJ/mol

Answer 1

【答案】A

【解析】已知：

①CH3COOH(l)＋2O2(g)＝2CO2(g)＋2H2O(l) ΔH1＝－870.3 kJ/mol

②C(s)＋O2(g)＝CO2(g) ΔH2＝－393.5 kJ/mol

③H2(g)＋1/2O2(g)＝H2O(l) ΔH3＝－285.8 kJ/mol

則根據(jù)蓋斯定律可知②×2+③×2－①即得到反應(yīng)2C(s)＋2H2(g)＋O2(g)＝CH3COOH(l)的反應(yīng)熱為－488.3 kJ/mol，答案選A。