1. The problem is to calculate the delta H. (1/2)A====> B 150 KJ/mol 3B====> 2C + D -125 KJ/mol E + A====> D 350 KJ/mol We have to find the delta H for: B + D====> E + 2C 2. The equation to use is just Hess's Law II 3. Now I have tried to combine these three reactions everyway I can think of but I can't get it the reaction B + D====> E + 2C Is it even possible to get it there because my D's cancel out. The closest I get is to is this B====> 2C + E What am I doing wrong? Any help would be appreciated.