(3)+△H=0 (苯)=100g/(78g·mol=1.282mol n(甲苯)=200g/(92g·mo)=2.174mol -R∑ng In xs △meS= =-R[n(苯)lnx(苯)+n(甲苯)lnx(甲苯 =-8.3145J·mol1·K1×1.282×ln0.2535+2.174×1n0.7465)mol =19.91J·K1