题目

Over the centuries, people have created many rituals (仪式) to accompany the consumption of their favourite drinks, tea and coffee. Just think of the Japanese tea ceremony, British afternoon tea or the morning coffee ritual in countless societies. Why are these drinks so popular? 【1】 In the modern world, the new caffeine delivery systems are canned energy drinks. And the more modern our world gets, the more we seem to need caffeine.Most people don’t think twice about their caffeine intake. 【2】 So the widespread use of caffeine is now a cause for concern among scientists and public 已知下列反应的反应热为：(1)CH3COOH（l）+2O2（g）=2CO2(g)+2H2O(l) △H1=-870.3KJ/mol(2)C(s)+O2(g)=CO2(g) △H2=-393.5KJ/mol   (3) H2(g)+O2(g)=H2O(l) △H3="-285.8KJ/mol " 试计算下列反应的焓变：2C(s)+2H2(g)+O2(g)=CH3COOH(l) △H=（   ）A．-488.3 KJ/molB．+488.3KJ/molC．-245.7KJ/molD．+245.7KJ/mol