2.13 已知下列反应在298K时的标准摩尔焓变:-|||-(1) (C)_(2)(H)_(2)(g)+5(O)_(2)(g)=4C(O)_(2)(g)+2(H)_(2)O(g) (Delta )_(t)(H)_(m)^theta =-2512kJcdot (mol)^-1-|||-(2) (H)_(2)(g)+(O)_(2)(g)=2(H)_(2)O(l) , .(Delta )_(t)(H)_(m)^theta =-572kJcdot (mol)^-1-|||-(3)C(石墨) +(O)_(2)(g)=C(O)_(2)(g) , .(Delta )_(t)(H)_(m)^theta =-394kJcdot (mol)^-1-|||-(4) _(2)O(g)=(H)_(2)O(l) , (Delta )_(t)(H)_(m)^theta =-44kJcdot (mol)^-1-|||-根据以上数据,计算△;H6(C2H2,g,298K)。