Question

Is a burning log an exothermic or endothermic event if the log is the system?

Answer 1

Exothermic reactions produce visible and sensible stimuli; they release their energy into their surroundings.
Endothermic reactions absorb energy; they do not release their energy for us to see or feel.

In regards to a burning log, can you see the fire and the smoke? If you go near it, can you feel the heat of the flame? Do you think the energy is being released in these forms, or is it being absorbed? That will give you your answer.