Why is it important to identify and rank criteria before designing a solution to an engineering
problem?

Answer:

5.6⋅10−^19  j

do you need the explaination?

It will appear as o2(g) as a reactant 

The internal energy of the system we can term it as total potential energy and kinetic energy. energy flows out of the surrounding from the system then we can say that the internal energy of the final state is lower than its initials. the sign of  δesystem is negative.δesystem = efinal - einitial=-ve  efinal  ∠einitial.