Question

imagine you could collect all of the heat that is transferred out of the two combustion systems shown in the image by the time that combustion ends and the system has cooled to room temperature.
for which of these two would that heat transfer be the same as the change in enthalpy of the combusting system?
neither of them
the fireplace burning only
the gas stove burning only
both of them
dont test me yet, i am trying to gain an understanding before attempting to answer this question.

Explanation:

• When wood burns in a fireplace, most of the heat is lost to the room (through convection and radiation) and not used for a specific, confined - purpose heat transfer like heating water in a controlled, insulated system.
• When natural gas burns to heat water, the system is designed to transfer the heat of combustion (enthalpy change of the combustion reaction) efficiently to the water. The heat transfer mechanism here is more about heating a specific substance (water) in a relatively closed - loop (in terms of heat transfer focus) compared to the fireplace where heat scatters to the room.

Answer:

Neither of them